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Statins and diabetes risk: Fact, fiction, and clinical implications
On february 28, 2012, the US Food and Drug Administration (FDA) updated its labeling requirements for statins. In addition to revising its recommendations for monitoring liver function and its alerts about reports of memory loss, the FDA also warned of the possibility of new-onset diabetes mellitus and worse glycemic control in patients taking statin drugs.1
This change stoked an ongoing debate about the risk of diabetes with statin use and the implications of such an effect. To understand the clinical consequences of this alert and its effect on treatment decisions, we need to consider the degree to which statins lower the risk of cardiovascular disease in patients at high risk (including diabetic patients), the magnitude of the risk of developing new diabetes while on statin therapy, and the ratio of risk to benefit in treated populations.
This review will discuss the evidence for this possible adverse effect and the implications for clinical practice.
DO STATINS CAUSE DIABETES?
Individual controlled trials dating back more than a decade have had conflicting results about new diabetes and poorer diabetic control in patients taking statins.
The West of Scotland Coronary Prevention Study (WOSCOPS)2 suggested that the incidence of diabetes was 30% lower in patients taking pravastatin (Pravachol) 40 mg/day than with placebo. However, this was not observed with atorvastatin (Lipitor) 10 mg/day in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid-Lowering Arm (ASCOT-LLA)3 in hypertensive patients or in the Collaborative Atorvastatin Diabetes Study (CARDS)4 in diabetic patients,4 nor was it noted with simvastatin (Zocor) 40 mg/day in the Heart Protection Study (HPS).5
The Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER),6 using the more potent agent rosuvastatin (Crestor) 20 mg/day in patients with elevated levels of C-reactive protein (CRP), was stopped early when an interim analysis found a 44% lower incidence of the primary end point. However, the trial also reported a 26% higher incidence of diabetes in follow-up of less than 2 years.
In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER),7 with a mean age at entry of 75, there was a 32% higher incidence of diabetes with pravastatin therapy.7
Results of meta-analyses
Several meta-analyses have addressed these differences.
Rajpathak et al8 performed a meta-analysis, published in 2009, of six trials—WOSCOPS,2 ASCOT-LLA,3 JUPITER,6 HPS,5 the Long-term Intervention With Pravastatin in Ischaemic Disease (LIPID) study,9 and the Controlled Rosuvastatin Multinational Study in Heart Failure (CORONA),10 with a total of 57,593 patients. They calculated that the incidence of diabetes was 13% higher (an absolute difference of 0.5%) in statin recipients, which was statistically significant. In their initial analysis, the authors excluded WOSCOPS, describing it as hypothesis-generating. The relative increase in risk was less—6%—and was not statistically significant when WOSCOPS was included.
Sattar et al,11 in a larger meta-analysis published in 2010, included 91,140 participants in 13 major statin trials conducted between 1994 and 2009; each trial had more than 1,000 patients and more than 1 year of follow-up.2,3,5–7,9,10,12–17 New diabetes was defined as physician reporting of new diabetes, new diabetic medication use, or a fasting glucose greater than 7 mmol/L (126 mg/dL).
New diabetes occurred in 2,226 (4.89%) of the statin recipients and in 2,052 (4.5%) of the placebo recipients, an absolute difference of 0.39%, or 9% more (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.02–1.17) (Figure 1).
The incidence of diabetes varied substantially among the 13 trials, with only JUPITER6 and PROSPER7 finding statistically significant increases in rates (26% and 32%, respectively). Of the other 11 trials, 4 had nonsignificant trends toward lower incidence,2,9,13,17 while the 7 others had nonsignificant trends toward higher incidence.
Does the specific statin make a difference?
Questions have been raised as to whether the type of statin used, the intensity of therapy, or the population studied contributed to these differences. Various studies suggest that factors such as using hydrophilic vs lipophilic statins (hydrophilic statins include pravastatin and rosuvastatin; lipophilic statins include atorvastatin, lovastatin, and simvastatin), the dose, the extent of lowering of low-density lipoprotein cholesterol (LDL-C), and the age or clinical characteristics of the population studied may influence this relationship.18–20
Yamakawa et al18 examined the effect of atorvastatin 10 mg/day, pravastatin 10 mg/day, and pitavastatin (Livalo) 2 mg/day on glycemic control over 3 months in a retrospective analysis. Random blood glucose and hemoglobin A1c levels were increased in the atorvastatin group but not in the other two.18
A prospective comparison of atorvastatin 20 mg vs pitavastatin 4 mg in patients with type 2 diabetes, presented at the American College of Cardiology’s 2011 annual meeting, reported a significant increase in fasting glucose levels with atorvastatin, particularly in women, but not with pitavastatin.19
In the Compare the Effect of Rosuvastatin With Atorvastatin on Apo B/Apo A-1 Ratio in Patients With Type 2 Diabetes Mellitus and Dyslipidaemia (CORALL) study,20 both high-dose rosuvastatin (40 mg) and high-dose atorvastatin (80 mg) were associated with significant increases in hemoglobin A1c, although the mean fasting glucose levels were not significantly different at 18 weeks of therapy.
A meta-analysis by Sattar et al11 did not find a clear difference between lipophilic statins (OR 1.10 vs placebo) and hydrophilic statins (OR 1.08). In analysis by statin type, the combined rosuvastatin trials were statistically significant in favor of a higher diabetes risk (OR 1.18, 95% CI 1.04–1.44). Nonsignificant trends were noted for atorvastatin trials (OR 1.14) and simvastatin trials (OR 1.11) and less so for pravastatin (OR 1.03); the OR for lovastatin was 0.98. This may suggest that there is a stronger effect with more potent statins or with greater lowering of LDL-C.
Meta-regression analysis in this study demonstrated that diabetes risk with statins was higher in older patients but was not influenced by body mass index or by the extent that LDL-C was lowered.
Statin dose as a risk factor
Intensive-dose statin therapy has been shown to reduce cardiovascular risk more than low-dose or moderate-dose therapy, thus supporting more aggressive treatment of LDL-C in higher-risk patients. However, some controlled studies comparing more-potent with less-potent statin regimens suggest that there may also be a higher risk of incident diabetes at higher doses.21–24
In a post hoc analysis of the Pravastatin or Atorvastatin Evaluation and Infection Therapy– Thrombolysis in Myocardial Infarction 22 (PROVE-IT TIMI 22) trial,21 patients who had experienced an acute coronary syndrome had a greater increase in hemoglobin A1c if treated with atorvastatin 80 mg/day than with pravastatin 40 mg/day.
Waters et al23 reported a higher risk of new diabetes with atorvastatin 80 mg than with placebo and a trend toward a higher risk with atorvastatin 80 mg than with atorvastatin 10 mg or simvastatin 20 mg.
In contrast, a review by Yousef et al24 of the data from the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study did not find a higher diabetes risk with more intensive statin therapy based on the magnitude of LDL-C reduction. A propensity-matched examination of deaths, recurrent acute ischemic events, or new diabetes in patients previously hospitalized with myocardial infarction found no differences in these end points each year out to 5 years. The risk of diabetes was in fact lower (but the difference was not statistically significant) in the high-dose groups out to 5 years. The risk of myocardial infarction or death was numerically different in the high-dose groups, but the difference was not statistically significant.
Preiss et al25 in 2011 performed a meta-analysis of the impact of intensity of statin therapy on diabetes risk. They examined data from 32,752 participants without diabetes at baseline in five randomized controlled trials with more than 1,000 participants and more than 1 year of follow-up, comparing high-dose therapy against moderate-dose statin therapy.21,22,26–28 New diabetes was considered present if there was an adverse event report of diabetes, if glucose-lowering drugs were started, or if two fasting plasma glucose measurements were higher than 7 mmol/L (126 mg/dL).
Diabetes developed in 1,449 (8.8%) of the intensive-therapy group and 1,300 (8.0%) of the moderate-therapy group (OR 1.12, 95% CI 1.04–1.22). In contrast, incident cardiovascular disease occurred in 3,134 (19.1%) of the intensive-therapy group and 3,550 (21.7%) of the moderate-therapy group (OR 0.84, 95% CI 0.75–0.94). Therefore, there was an 0.8% absolute increase in diabetes cases on high-dose statins and a 2.6% absolute reduction in adverse cardiovascular events.
CAUTION IN INTERPRETING THESE DATA
There are many reasons for caution in interpreting these studies.
The trials were not designed to look for diabetes
The data supporting the relationship between statin therapy and higher risk of diabetes are primarily from observational studies. These studies were not prospectively designed to address this question, and we therefore need to view this as association and not as causation.
The definition of diabetes varied between trials, and new-onset diabetes was often not rigorously screened for. In many trials the outcome of diabetes was at least partially based on nonstandardized, nonadjudicated physician reporting.
Consequently, if statins reduce the risk of diabetes, the results from WOSCOPS may overstate the reduction, since this study used a non-standard definition of incident diabetes (fasting plasma glucose > 126 mg/dL plus a > 36 mg/dL increase from baseline). When Sattar et al11 reanalyzed WOSCOPS data using a more standard definition, they found a smaller effect.
On the other hand, nonstandardized physician reporting may overstate an adverse effect. Sattar et al11 also found that when fasting plasma glucose levels alone were used as the definition for diabetes, the overall risk was attenuated and was no longer statistically significant (OR 1.07, 95% CI 0.97–1.17).
Perhaps statin therapy uncovers diabetes only in people at risk of diabetes
Perhaps statin therapy uncovers diabetes only in people at higher baseline risk of developing diabetes. Therefore, this adverse effect may be restricted to certain groups and not applicable to the general population.
In JUPITER, one of the two trials in which, on independent analysis, statin use was associated with new diabetes, 77% of patients in the rosuvastatin group who developed diabetes had impaired fasting glucose at entry and therefore were at higher risk of developing diabetes.6
Possibly, the relationship is driven by preexisting metabolic syndrome or other risk factors for diabetes. In the two studies that reported a statistically significantly higher incidence of new diabetes, more than 40% of patients in JUPITER met the criteria for metabolic syndrome, and metabolic syndrome, which increases in prevalence with age, was likely more prominent in the elderly population in PROSPER.
Waters et al23 grouped patients according to whether they had risk factors for diabetes (impaired fasting glucose, obesity, elevated triglycerides, and hypertension) and found that those who had none or one of these risk factors had no difference in the rate of new-onset diabetes with either moderate or intensive statin therapy, but the risk was pronounced in those who had three or four risk factors.
Ridker et al29 reanalyzed the JUPITER data from patients who did not have cardiovascular disease at baseline. Overall, for every 54 new cases of diabetes in follow-up, 134 cardiovascular events or deaths were prevented. In subgroup analysis, those who had one or more risk factors for diabetes at baseline (metabolic syndrome, impaired fasting glucose, obesity, or hemoglobin A1c > 6%) had a 39% reduction in the primary end point and a 28% increase in new diabetes. Those who had none of these risk factors had a 52% lower rate of cardiovascular events but no increase in diabetes.
Other confounding factors
Bias and confounding factors are difficult to control for in studies without prospectively defined, recognized, and analyzed outcomes.
Although it may be a bit of a stretch, residual confounding factors such as myalgia side effects while on statins may reduce exercise in the statin-treatment groups. Perhaps a change to a healthier lifestyle after cardiovascular events may be more common in placebo groups. Improved survival with statins may allow more people at risk of diabetes to live longer and present with the diagnosis.30
POSSIBLE EXPLANATIONS, BUT NO UNIFYING MECHANISM
If mechanisms could be identified to explain the association between statins and diabetes, this would strengthen the argument that it is a cause-and-effect relationship. Many explanations have been proposed as to how statins may influence glucose metabolism and insulin sensitivity.31–34 These are possible explanations based on other observations.
In theory, statins may improve insulin sensitivity via their anti-inflammatory effect, since inflammatory markers and proinflammatory cytokines have been linked with insulin resistance. However, other effects of statins may adversely affect glycemic control.
In vivo analysis has shown that some but not all statins increase insulin levels and decrease insulin sensitivity in a dose-dependent fashion. Some statins decrease adiponectin and may worsen glycemic control through loss of adiponectin’s proposed protective anti-proliferative and antiangiogenic properties. In vitro studies and animal studies have demonstrated a decrease in expression of insulin-responsive glucose transporter 4 (GLUT4) with atorvastatin, and an increase in GLUT1. It has been hypothesized that reduction in isoprenoid biosynthesis or decreased insulin signaling may explain these effects and that changes in glucose transport in adipocytes may cause insulin resistance. Other studies suggest that dysregulation of cellular cholesterol may attenuate beta-cell function. Impaired biosynthesis of ubiquinones may result in delayed production of adenosine triphosphate and consequently diminish insulin release.
But different effects have been reported for atorvastatin, simvastatin, and pravastatin, arguing against a unifying explanation or, alternatively, suggesting that differences in lipophilicity and potency among statins are important. Hydrophilic statins may be less likely to be taken up by extrahepatic cells such as pancreatic cells and adipocytes, possibly lessening these effects. However, the strong association between rosuvastatin (which is hydrophilic) and new diabetes would not support this hypothesis.
Despite these speculations, lack of conformity in response to different statins and discrepancies in the clinical outcomes noted in trials fail to clearly identify a common causative mechanism.
OTHER COMMON THERAPIES MAY INFLUENCE GLYCEMIC CONTROL
Statins are not the first drugs for reducing cardiovascular risk that have been shown to affect glucose levels during treatment.
Niacin
Niacin has been known to increase glucose levels but has long been used as a treatment for dyslipidemia despite this caution. Reduced glycemic control during niacin treatment in diabetic patients does not seem to alter the beneficial effects of treatment.35–37
In a post hoc analysis of the Coronary Drug Project (CDP), in patient subgroups defined by baseline fasting plasma glucose and compared with placebo, niacin reduced the 6-year risk of recurrent myocardial infarction and the combined end point of coronary heart disease death or nonfatal myocardial infarction similarly (interactive P value nonsignificant) across all levels of baseline fasting plasma glucose, including levels of 126 mg/dL or higher at study entry.36
In another post hoc analysis of CDP patient subgroups defined by the change in glycemic status from baseline to 1 year, niacin reduced the 6-year risk of the same end points similarly (interactive P value nonsignificant) across all levels of change in fasting plasma glucose from baseline to year 1, whether baseline fasting plasma glucose levels decreased, stayed the same, or increased to 10 mg/dL or higher on niacin therapy.36
Therefore, the beneficial effect of niacin of reducing the rate of recurrent nonfatal myocardial infarction and coronary heart disease events was not significantly diminished when impaired fasting glucose or diabetes was present when therapy was started or by on-therapy increases from baseline fasting plasma glucose.
In addition, on-therapy changes in glycemic control may be dose-related and minimized by surveillance and therapy adjustments. The Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial (ADVENT)38 found that changes in glycemic control were minimal as measured by fasting glucose and hemoglobin A1c; were associated with a higher niacin dose (1.5 g/day vs 1 g/day); and, when present, were successfully managed by adjusting the diabetes treatment regimen.
Antihypertensive drugs
Diuretics as well as beta-blockers have been reported to increase the incidence of diabetes in patients with hypertension.15,38–40
A retrospective longitudinal cohort study40 in 2009 examined the development of new-onset diabetes (defined as a new ICD-9 code for diabetes or initiation of diabetes treatment) in 24,688 treated hypertensive patients without diabetes at baseline; 4,385 (17.8%) of the patients developed diabetes. After adjusting for sex and age, the risk of new diabetes was significant in users of diuretics (OR 1.10), beta-blockers (OR 1.12), and calcium channel blockers (OR 1.10) compared with users of angiotensin-converting enzyme inhibitors, (OR 0.92), angiotensin receptor blockers (OR 0.90), or alpha-blockers (OR 0.88).
However, the increase in blood glucose does not seem to attenuate the beneficial effects of reducing cardiovascular events. In the Antihypertensive and Lipid-lowering Treatment to Prevent Heart Attack Trial (ALLHAT),15 a long-term follow-up of those developing new-onset diabetes while taking chlorthalidone (Hygroton) found no difference in the risk of death from cardiovascular disease or from any cause (hazard ratio = 1.04).15
CLINICAL IMPLICATIONS
Balancing the benefits and risks of statins
It is important to examine how the 0.4% increase in absolute risk of new-onset diabetes as calculated in meta-analyses compares with the benefits of statin treatment in terms of cardiovascular risk reduction.
Using data from the Cholesterol Treatment Trialists (CTT) meta-analysis of statin trials in 71,370 participants, Sattar et al11 estimated that statin treatment is associated with 5.4 fewer deaths from coronary heart disease and cases of nonfatal myocardial infarction per 255 patients treated over 4 years for each 1-mmol/L (39 mg/dL) reduction in LDL-C compared with controls. The benefit would be even greater if stroke, revascularization, and hospitalization are included as end points. This benefit is contrasted with the risk of developing 1 additional case of diabetes for every 255 patients treated with statins over the same period.
Preiss et al25 calculated that there were 2 more cases of diabetes per 1,000 patient-years in patients receiving intensive doses than in those receiving moderate doses (18.9 vs 16.9), corresponding to 1 additional case of diabetes for every 498 patients treated per year. However, there were 6.5 fewer first major cardiovascular events per 1,000 patient-years (44.5 vs 51.0), corresponding to a number needed to treat per year to prevent 1 cardiovascular event of 155. Most of the benefit was due to fewer revascularizations, followed by nonfatal myocardial infarctions. The 12% increase in new diabetes with high-dose therapy contrasted with a 16% reduction in new cardiovascular disease combined events (OR 0.84, 95% CI 0.75–0.94).
As previously noted, in the JUPITER trial, the benefits of preventing cardiovascular events with statin therapy outweighed the risk of new diabetes in people both with and without baseline risk factors for diabetes.29 Similar to the observations with niacin and some antihypertensive drugs, the increase in blood glucose with statins does not appear to reduce the benefits of cardiovascular risk reduction in these patients at moderate to high risk, even when used at high doses.
People with diabetes need aggressive lipid-lowering—with statins
Diabetes is a coronary heart disease risk equivalent and is associated with high risk of cardiovascular events.41–46 Overall, the risk for these adverse events is two to four times greater in people with diabetes than without. Atherosclerosis-related events account for approximately 65% to 75% of all deaths in people with diabetes, and 75% of these events are coronary. Lipid abnormalities are strongly correlated with the risk of cardiovascular disease in people with diabetes, and aggressive treatment of risk factors, particularly lipid abnormalities, has been shown to reduce this risk.47–49 And data from multiple clinical trials support the use of statins to lower LDL-C as the first-line therapy for dyslipidemia in people with diabetes, just as it is in the general population.3–7,9,13,23,50–61
Analyses of diabetic subgroups encompassing 18,000 to 20,000 patients in the large statin trials have clearly demonstrated the benefits of statin therapy. A recent metaanalysis of 10 placebo-controlled trials that included approximately 16,000 patients with diabetes and 54,000 without diabetes demonstrated a 30% reduction in coronary heart disease, a 19% reduction in strokes, and a 12% reduction in mortality.54 Furthermore, in another meta-analysis of 14 trials, a similar 22% reduction in coronary heart disease was noted in people with diabetes whether or not they had a history of cardiovascular disease.55
Therefore, aggressive treatment of lipid abnormalities with statins as primary treatment has generally been adopted as a standard of care in diabetic patients, particularly those with clinical cardiovascular disease or one or more risk factors. The Adult Treatment Panel III guidelines recommend a minimum LDL-C goal of less than 100 mg/dL and a goal of less than 70 mg/dL as an option for patients with diabetes (Table 1).41,62 Similar recommendations have been issued by the American Diabetes Association together with the American College of Cardiology (Table 2),30 the American Diabetes Association by itself,63 and the American Academy of Pediatrics.6
Is new-onset diabetes as dangerous as established diabetes?
In studies to date, there did not appear to be more events in those who developed new-onset diabetes.
Waters et al,24 evaluating three trials of high-dose atorvastatin therapy, found that major cardiovascular events occurred in 11.3% of those with new-onset diabetes, 10.8% of those without new-onset diabetes (HR 1.02, 95% CI 0.77–1.35), and 17.5% of those who had diabetes at baseline.
Therefore, it may not be appropriate to extrapolate the glucose changes seen on statin therapy to an equivalent increase in adverse cardiovascular events as seen in other diabetic patients. The beneficial reduction in cardiovascular events does not appear to be diminished in those developing diabetes. It is not clear that the increase in glucose on statins has the same implications of a new diagnosis of diabetes. Does this elevation in glucose represent true diabetes or some downstream effect? For example, thiazide diuretics have been known to increase blood glucose levels, but the levels drop when these drugs are discontinued, even after many years of treatment.
On the other hand, it is possible that follow-up of 5 years or less in clinical trials has not allowed sufficient time to examine the influence of the increase in new-onset diabetes on future cardiovascular events. In addition, because of the widespread use of statins across a broad range of cardiovascular risk, even if the effect is small in absolute terms, the potential adverse effects are magnified, particularly in a low-risk population in which the cardiovascular benefits are smaller.
The association is real, but questions remain
In view of the evidence, it is difficult to refute that an association exits between statin use and new-onset diabetes, at least in some subgroups. The dose response noted in some studies further reinforces the conclusion that the association is real. However, many questions remain unanswered regarding mechanism of effect, whether there are differences depending on the particular statin or dose used, or differential effects in the populations treated (such as patients with metabolic syndrome or the elderly).
Until the contradictory observations can be resolved and plausible mechanisms of action elucidated, causality cannot be established. From a clinical standpoint there is no current evidence suggesting that the elevations in blood glucose seen while on lipid-lowering or blood-pressure-lowering therapy are associated with an increased risk of cardiovascular events or that they attenuate the beneficial effects of the therapy.
Statins should continue to be used in patients at high risk
Until further studies are done, statins should continue to be used, after assessing the risks and the benefits.
Primary prevention patients at moderate to high risk and secondary prevention patients stand to gain from statin therapy, and it should not be denied or doses reduced on the basis of concerns about the development of new-onset diabetes. The recognized modest risk of developing diabetes does not appear to blunt the cardioprotective effects of statin therapy in these moderate-to high-risk groups.
Rather than stop statins in patients at risk of diabetes such as the elderly or those with prediabetes, insulin resistance, or metabolic syndrome who are on therapy for appropriate reasons, it is reasonable to continue these drugs, monitoring glucose more closely and emphasizing the importance of weight reduction, diet, and aerobic exercise for preventing diabetes. The Diabetes Prevention Program Research Group, for example, reduced the incidence of diabetes by 58% over 2.8 years of follow-up with intensive lifestyle interventions (a low-calorie, low-fat diet plus moderate physical activity 150 minutes per week) vs usual care in at-risk populations.65
Should statins be used more cautiously in patients at lower risk?
The most recent Cholesterol Treatment Trialists meta-analysis of 27 randomized clinical trials (22 placebo-controlled, 134,537 people; 5 high-dose vs low-dose, 39,612 people) reported that reducing LDL-C with statins lowered cardiovascular risk even in low-risk patients.66 Overall, there were 21% fewer major cardiovascular events (coronary heart disease, stroke, or coronary revascularization) for every 1-mmol/L reduction in LDL-C.
The proportional reduction in events was at least as large in the two lowest-risk groups (estimated 5-year risk of < 5% and 5% to < 10%, 53,152 people) as in the higher-risk groups. This was reflected mainly in fewer nonfatal myocardial infarctions and coronary revascularizations. In these groups, the absolute reduction in risk for each 1-mmol/L reduction in LDL-C was 11 per 1,000 patients over 5 years. Even in this low-risk population, the reduction in cardiovascular risk seems to compare favorably with the small estimated increase risk of diabetes.
However, even in the lowest-risk group studied, the average baseline LDL-C level was greater than 130 mg/dL.
Therefore, in groups in which the benefits of statins on cardiovascular risk reduction are less robust (eg, low-risk primary prevention groups without significant elevations in LDLC, particularly the elderly), it would not be difficult to justify the case for more cautious use of statin therapy. If statins are used in these low-risk groups, restricting their use to those with at least moderate LDL-C elevation, using less aggressive LDL-C-lowering targets, and regular monitoring of fasting glucose seem reasonable until further information is available.
- US Food and Drug Administration. Statin drugs—drug safety communication: class labeling change. February 28, 2012. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm293670.htm.
- Freeman DJ, Norrie J, Sattar N, et al. Pravastatin and the development of diabetes mellitus: evidence for a protective treatment effect in the West of Scotland Coronary Prevention Study. Circulation 2001; 103:357–362.
- Sever PS, Dahlof B, Poulter NR, et al; ASCOT investigators. Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-than-average cholesterol concentrations, in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid Lowering Arm (ASCOT-LLA): a multicentre randomised controlled trial. Lancet 2003; 361:1149–1158.
- Colhoun HM, Betteridge DJ, Durrington PN, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004; 364:685–696.
- Collins R, Armitage J, Parish S, Sleigh P, Peto R; for the Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol-lowering with simvastatin in 5963 people with diabetes: a randomised placebo-controlled trial. Lancet 2003; 361:2005–2016.
- Ridker PM, Danielson E, Fonseca FA, et al. Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein. N Engl J Med 2008; 359:2195–2207.
- Shepherd J, Blauw GJ, Murphy MB, et al; PROSPER Study Group. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002; 360:1623–1630.
- Rajpathak SN, Kumbhani DJ, Crandall J, Barzilai N, Alderman M, Ridker PM. Statin therapy and risk of developing type 2 diabetes: a meta-analysis. Diabetes Care 2009; 32:1924–1929.
- Keech A, Colquhoun D, Best J, et al. Secondary prevention of cardiovascular events with long-term pravastatin in patients with diabetes or impaired fasting glucose—results from the LIPID trial. Diabetes Care 2003; 26:2713–2721.
- Kjekshus J, Apetrei E, Barrios V, et al. Rosuvastatin in older patients with systolic heart failure. N Engl J Med 2007; 357:2248–2261.
- Sattar N, Preiss D, Murray HM, et al. Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials. Lancet 2010; 375:735–742.
- Nakamura H, Arakawa K, Itakura H, et al. Primary prevention of cardiovascular disease with pravastatin in Japan (MEGA Study): a prospective randomised controlled trial. Lancet 2006; 368:1155–1163.
- Downs JR, Clearfield M, Weis S, et al. Primary prevention of acute coronary events with lovastatin in men and women with average cholesterol levels: results of AFCAPS/TexCAPS. Air Force/Texas Coronary Atherosclerosis Prevention Study. JAMA 1998; 279:1615–1622.
- Scandinavian Simvastatin Survival Study study group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet 1994; 344:1383–1389.
- Barzilay JI, Davis BR, Pressel SL, et al; ALLHAT Collaborative Research Group. Long-term effects of incident diabetes mellitus on cardiovascular outcomes in people treated for hypertension: the ALLHAT Diabetes Extension Study. Circ Cardiovasc Qual Outcomes 2012; 5:153–162.
- Tavazzi L, Maggioni AP, Marchioli R, et al. Effect of rosuvastatin in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial. Lancet 2008; 372:1231–1239.
- GISSI Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico). Results of the low-dose (20 mg) pravastatin GISSI Prevenzione trial in 4271 patients with recent myocardial infarction: do stopped trials contribute to overall knowledge? Ital Heart J 2000; 1:810–820.
- Yamakawa T, Takano T, Tanaka S, Kadonosono K, Terauchi Y. Influence of pitavastatin on glucose tolerance in patients with type 2 diabetes mellitus. J Atheroscler Thromb 2008; 15:269–275.
- Kryzhanovski V, Gumprecht J, Zhu B, Yu CY, Hounslow N, Sponseller CA. Atorvastatin but not pitavastatin significantly increases fasting plasma glucose in patients with type 2 diabetes and combined dyslipidemia (abstract). J Am Coll Cardiol 2011; 57:E575.
- Simsek S, Schalkwijk CG, Wolffenbuttel BH. Effects of rosuvastatin and atorvastatin on glycaemic control in type 2 diabetes—the CORALL study. Diabet Med 2012; 29:628–631.
- Sabatine MS, Morrow DA, Giugliano RP, et al. Implications of upstream glycoprotein IIb/IIIa inhibition and coronary artery stenting in the invasive management of unstable angina/non-ST-elevation myocardial infarction: a comparison of the Thrombolysis In Myocardial Infarction (TIMI) IIIB trial and the Treat angina with Aggrastat and determine Cost of Therapy with Invasive or Conservative Strategy (TACTICS)-TIMI 18 trial. Circulation 2004; 110(suppl III):834–880.
- Shepherd J, Barter P, Carmena R, et al. Effect of lowering LDL cholesterol substantially below currently recommended levels in patients with coronary heart disease and diabetes: the Treating to New Targets (TNT) study. Diabetes Care 2006; 29:1220–1226.
- Waters DD, Ho JE, DeMicco DA, et al. Predictors of new-onset diabetes in patients treated with atorvastatin: results from 3 large randomized clinical trials. J Am Coll Cardiol 2011; 57:1535–1545.
- Yousef A, Tu JV, Wang J, Donovan L, Ko DT. The association of intensive statin therapy on long-term risks of cardiovascular events and diabetes following acute myocardial infarction (abstract). Circulation 2012; 125:e859.
- Preiss D, Seshasai SR, Welsh P, et al. Risk of incident diabetes with intensive-dose compared with moderate-dose statin therapy: a metaanalysis. JAMA 2011; 305:2556–2564.
- de Lemos JA, Blazing MA, Wiviott SD, et al; A to Z Investigators. Early intensive vs a delayed conservative simvastatin strategy in patients with acute coronary syndromes: phase Z of the A to Z trial. JAMA 2004; 292:1307–1316.
- Pedersen TR, Faegeman O, Kastelein JJ, et al; Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL) Study Group. High-dose atorvastatin vs usual-dose simvastatin for secondary prevention after myocardial infarction: the IDEAL study: a randomized controlled trial. JAMA 2005; 294:2437–2445.
- Armitage J, Bowman L, Wallendszus K, et al; Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH) Collaborative Group. Intensive lowering of LDL cholesterol with 80 mg versus 20 mg simvastatin daily in 12,064 survivors of myocardial infarction: a double-blind randomised trial. Lancet 2010; 37:1658–1669.
- Ridker PM, Pradhan A, MacFadyen JG, Libby P, Glynn RJ. Cardiovascular benefits and diabetes risks of statin therapy in primary prevention: an analysis from the JUPITER trial. Lancet 2012; 380:565–571.
- Brunzell JD, Davidson M, Furberg CD, et al; American Diabetes Association; American College of Cardiology Foundation. Lipoprotein management in patients with cardiometabolic risk: consensus statement from the American Diabetes Association and the American College of Cardiology Foundation. Diabetes Care 2008; 31:811–822.
- Koh KK, Quon MJ, Han SH, Lee Y, Kim SJ, Shin EK. Atorvastatin causes insulin resistance and increases ambient glycemia in hypercholesterolemic patients. J Am Coll Cardiol 2010; 55:1209–1216.
- Koh KK, Quon MJ, Han SH, et al. Differential metabolic effects of pravastatin and simvastatin in hypercholesterolemic patients. Atherosclerosis 2009; 204:483–490.
- Nakata M, Nagasaka S, Kusaka I, Matsuoka H, Ishibashi S, Yada T. Effects of statins on the adipocyte maturation and expression of glucose transporter 4 (SLC2A4): implications in glycaemic control. Diabetologia 2006; 49:1881–1892.
- Yada T, Nakata M, Shiraishi T, Kakei M. Inhibition by simvastatin, but not pravastatin, of glucose-induced cytosolic Ca2+ signalling and insulin secretion due to blockade of L-type Ca2+ channels in rat islet beta-cells. Br J Pharmacol 1999; 126:1205–1213.
- Guyton JR, Fazio S, Adewale AJ, et al. Effect of extended-release niacin on new-onset diabetes among hyperlipidemic patients treated with ezetimibe/simvastatin in a randomized controlled trial. Diabetes Care 2012; 35:857–860.
- Canner PL, Furberg CD, Terrin ML, McGovern ME. Benefits of niacin by glycemic status in patients with healed myocardial infarction (from the Coronary Drug Project). Am J Cardiol 2005; 95:254–257.
- Grundy SM, Vega GL, McGovern ME, et al; Diabetes Multicenter Research Group. Efficacy, safety, and tolerability of once-daily niacin for the treatment of dyslipidemia associated with type 2 diabetes: results of the Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial. Arch Intern Med 2002; 162:1568–1576.
- Gupta AK, Dahlof B, Dobson J, Sever PS, Wedel H, Poulter NRAnglo-Scandinavian Cardiac Outcomes Trial Investigators. Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial—Blood Pressure Lowering Arm and the relative influence of antihypertensive medication. Diabetes Care 2008; 31:982–988.
- Elliott WJ, Meyer PM. Incident diabetes in clinical trials of antihypertensive drugs: a network meta-analysis. Lancet 2007; 369:201–207.
- Jong JP, Chang MH, Tien L, et al. Antihypertensive drugs and new-onset diabetes: a retrospective longitudinal cohort study. Cardiovasc Ther 2009; 27:159–163.
- Third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation 2002; 106:3143–3421.
- Norhammar A, Tenerz A, Nilsson G, et al. Glucose metabolism in patients with acute myocardial infarction and no previous diagnosis of diabetes mellitus: a prospective study Lancet 2002; 359:2140–2144.
- Haffner SM, Lehto S, Ronnemaa T, Pyorala K, Laakso M. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med 1998; 339:229–234.
- Sprafka JM, Burke GL, Folsom AR, McGovbern PG, Hahn LP. Trends in prevalence of diabetes mellitus in patients with myocardial infarction and effect of diabetes on survival. The Minnesota Heart Survey. Diabetes Care 1991; 14:537–543.
- Geiss LS, Herman WH, Smith PJ. Mortality in non-insulin-dependent diabetes. In:Harris MI, Cowie CC, Stern MP, et al, editors. Diabetes in America. 2nd ed. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, 1995:233–257.
- Stamler J, Vaccaro O, Neaton JD, Wentworth D. Diabetes, other risk factors, and 12-yr cardiovascular mortality for men screened in the Multiple Risk Factor Intervention Trial. Diabetes Care 1993; 16:434–444.
- Turner RC, Millns H, Neil HA, et al. Risk factors for coronary artery disease in non-insulin dependent diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS: 23). BMJ 1998; 316:823–828.
- Gaede P, Vedel P, Larsen N, Jensen GV, Parving HH, Pedersen O. Multifactorial intervention and cardiovascular disease in patients with type 2 diabetes. N Engl J Med 2003; 348:383–393.
- Gaede P, Pederson O. Intensive integrated therapy of type 2 diabetes: implications for long-term prognosis. Diabetes 2004; 53:S39–S47.
- Goldberg RB, Mellies MJ, Sacks FM, et al. Cardiovascular events and their reduction with pravastatin in diabetic and glucose-intolerant myocardial infarction survivors with average cholesterol levels: subgroup analyses in the cholesterol and recurrent events (CARE) trial. The Care Investigators. Circulation 1998; 98:2513–2519.
- Pyðrälä K, Pedersen TR, Kjekshus J, Faergeman O, Olsson AG, Thorgeirsson G. Cholesterol lowering with simvastatin improves prognosis of diabetic patients with coronary heart disease. A subgroup analysis of the Scandinavian Simvastatin Survival Study (4S). Diabetes Care 1997; 20:614–620.
- Vijan S, Hayward RA; American College of Physicians. Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians. Ann Intern Med 2004; 140:650–658.
- Baigent C, Keech A, Kearney PM, et al; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005; 366:1267–1278. Errata in Lancet 2008; 371:2084, Lancet 2005; 366:1358.
- Brugts JJ, Yetgin T, Hoeks SE, et al. The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials. BMJ 2009; 338:b2376.
- Kearney PM, Blackwell L, Collins R, Keech A, Simes J, Baigent C; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis. Lancet 2008; 371:117–125.
- Nissen SE, Nicholls SJ, Sipahi I, et al; ASTEROID Investigators. Effect of very high-intensity statin therapy on regression of coronary atherosclerosis: the ASTEROID trial. JAMA 2006; 295:1556–1565.
- Cannon CP, Braunwald E, McCabe CH, et al; Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis in Myocardial Infarction 22 Investigators. Intensive versus moderate lipid lowering with statins after acute coronary syndromes et al. N Engl J Med 2004; 350:1495–1504.
- LaRosa JC, Grundy SM, Waters DD, et al; Treating to New Targets (TNT) Investigators. Intensive lipid lowering with atorvastatin in patients with stable coronary disease. N Engl J Med 2005; 352:1425–1435.
- Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002; 360:7–22.
- Baigent C, Blackwell L, Emberson J, et al; Cholesterol Treatment Trialists’ (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet 2010; 376:1670–1681.
- LIPID Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. The Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. N Engl J Med 1998; 339:1349–1357.
- Grundy SM, Cleeman JI, Bairey Merz CN, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 2004; 110:227–239.
- American Diabetes Association. Executive summary: standards of medical care in diabetes—2012. Diabetes Care 2012; 35(suppl 1):S5–S10.
- Daniels SR, Greer FR; Committee on Nutrition. Lipid screening and cardiovascular health in childhood. Pediatrics 2008; 122:198–208.
- Knowler WC, Barrett-Connor E, Fowler SE, et al; Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346:393–403.
- Cholesterol Treatment Trialists’ (CTT) Collaborators; Mihaylova B, Emberson J, Blackwell L, et al. The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. Lancet 2012; 380:581–590.
On february 28, 2012, the US Food and Drug Administration (FDA) updated its labeling requirements for statins. In addition to revising its recommendations for monitoring liver function and its alerts about reports of memory loss, the FDA also warned of the possibility of new-onset diabetes mellitus and worse glycemic control in patients taking statin drugs.1
This change stoked an ongoing debate about the risk of diabetes with statin use and the implications of such an effect. To understand the clinical consequences of this alert and its effect on treatment decisions, we need to consider the degree to which statins lower the risk of cardiovascular disease in patients at high risk (including diabetic patients), the magnitude of the risk of developing new diabetes while on statin therapy, and the ratio of risk to benefit in treated populations.
This review will discuss the evidence for this possible adverse effect and the implications for clinical practice.
DO STATINS CAUSE DIABETES?
Individual controlled trials dating back more than a decade have had conflicting results about new diabetes and poorer diabetic control in patients taking statins.
The West of Scotland Coronary Prevention Study (WOSCOPS)2 suggested that the incidence of diabetes was 30% lower in patients taking pravastatin (Pravachol) 40 mg/day than with placebo. However, this was not observed with atorvastatin (Lipitor) 10 mg/day in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid-Lowering Arm (ASCOT-LLA)3 in hypertensive patients or in the Collaborative Atorvastatin Diabetes Study (CARDS)4 in diabetic patients,4 nor was it noted with simvastatin (Zocor) 40 mg/day in the Heart Protection Study (HPS).5
The Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER),6 using the more potent agent rosuvastatin (Crestor) 20 mg/day in patients with elevated levels of C-reactive protein (CRP), was stopped early when an interim analysis found a 44% lower incidence of the primary end point. However, the trial also reported a 26% higher incidence of diabetes in follow-up of less than 2 years.
In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER),7 with a mean age at entry of 75, there was a 32% higher incidence of diabetes with pravastatin therapy.7
Results of meta-analyses
Several meta-analyses have addressed these differences.
Rajpathak et al8 performed a meta-analysis, published in 2009, of six trials—WOSCOPS,2 ASCOT-LLA,3 JUPITER,6 HPS,5 the Long-term Intervention With Pravastatin in Ischaemic Disease (LIPID) study,9 and the Controlled Rosuvastatin Multinational Study in Heart Failure (CORONA),10 with a total of 57,593 patients. They calculated that the incidence of diabetes was 13% higher (an absolute difference of 0.5%) in statin recipients, which was statistically significant. In their initial analysis, the authors excluded WOSCOPS, describing it as hypothesis-generating. The relative increase in risk was less—6%—and was not statistically significant when WOSCOPS was included.
Sattar et al,11 in a larger meta-analysis published in 2010, included 91,140 participants in 13 major statin trials conducted between 1994 and 2009; each trial had more than 1,000 patients and more than 1 year of follow-up.2,3,5–7,9,10,12–17 New diabetes was defined as physician reporting of new diabetes, new diabetic medication use, or a fasting glucose greater than 7 mmol/L (126 mg/dL).
New diabetes occurred in 2,226 (4.89%) of the statin recipients and in 2,052 (4.5%) of the placebo recipients, an absolute difference of 0.39%, or 9% more (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.02–1.17) (Figure 1).
The incidence of diabetes varied substantially among the 13 trials, with only JUPITER6 and PROSPER7 finding statistically significant increases in rates (26% and 32%, respectively). Of the other 11 trials, 4 had nonsignificant trends toward lower incidence,2,9,13,17 while the 7 others had nonsignificant trends toward higher incidence.
Does the specific statin make a difference?
Questions have been raised as to whether the type of statin used, the intensity of therapy, or the population studied contributed to these differences. Various studies suggest that factors such as using hydrophilic vs lipophilic statins (hydrophilic statins include pravastatin and rosuvastatin; lipophilic statins include atorvastatin, lovastatin, and simvastatin), the dose, the extent of lowering of low-density lipoprotein cholesterol (LDL-C), and the age or clinical characteristics of the population studied may influence this relationship.18–20
Yamakawa et al18 examined the effect of atorvastatin 10 mg/day, pravastatin 10 mg/day, and pitavastatin (Livalo) 2 mg/day on glycemic control over 3 months in a retrospective analysis. Random blood glucose and hemoglobin A1c levels were increased in the atorvastatin group but not in the other two.18
A prospective comparison of atorvastatin 20 mg vs pitavastatin 4 mg in patients with type 2 diabetes, presented at the American College of Cardiology’s 2011 annual meeting, reported a significant increase in fasting glucose levels with atorvastatin, particularly in women, but not with pitavastatin.19
In the Compare the Effect of Rosuvastatin With Atorvastatin on Apo B/Apo A-1 Ratio in Patients With Type 2 Diabetes Mellitus and Dyslipidaemia (CORALL) study,20 both high-dose rosuvastatin (40 mg) and high-dose atorvastatin (80 mg) were associated with significant increases in hemoglobin A1c, although the mean fasting glucose levels were not significantly different at 18 weeks of therapy.
A meta-analysis by Sattar et al11 did not find a clear difference between lipophilic statins (OR 1.10 vs placebo) and hydrophilic statins (OR 1.08). In analysis by statin type, the combined rosuvastatin trials were statistically significant in favor of a higher diabetes risk (OR 1.18, 95% CI 1.04–1.44). Nonsignificant trends were noted for atorvastatin trials (OR 1.14) and simvastatin trials (OR 1.11) and less so for pravastatin (OR 1.03); the OR for lovastatin was 0.98. This may suggest that there is a stronger effect with more potent statins or with greater lowering of LDL-C.
Meta-regression analysis in this study demonstrated that diabetes risk with statins was higher in older patients but was not influenced by body mass index or by the extent that LDL-C was lowered.
Statin dose as a risk factor
Intensive-dose statin therapy has been shown to reduce cardiovascular risk more than low-dose or moderate-dose therapy, thus supporting more aggressive treatment of LDL-C in higher-risk patients. However, some controlled studies comparing more-potent with less-potent statin regimens suggest that there may also be a higher risk of incident diabetes at higher doses.21–24
In a post hoc analysis of the Pravastatin or Atorvastatin Evaluation and Infection Therapy– Thrombolysis in Myocardial Infarction 22 (PROVE-IT TIMI 22) trial,21 patients who had experienced an acute coronary syndrome had a greater increase in hemoglobin A1c if treated with atorvastatin 80 mg/day than with pravastatin 40 mg/day.
Waters et al23 reported a higher risk of new diabetes with atorvastatin 80 mg than with placebo and a trend toward a higher risk with atorvastatin 80 mg than with atorvastatin 10 mg or simvastatin 20 mg.
In contrast, a review by Yousef et al24 of the data from the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study did not find a higher diabetes risk with more intensive statin therapy based on the magnitude of LDL-C reduction. A propensity-matched examination of deaths, recurrent acute ischemic events, or new diabetes in patients previously hospitalized with myocardial infarction found no differences in these end points each year out to 5 years. The risk of diabetes was in fact lower (but the difference was not statistically significant) in the high-dose groups out to 5 years. The risk of myocardial infarction or death was numerically different in the high-dose groups, but the difference was not statistically significant.
Preiss et al25 in 2011 performed a meta-analysis of the impact of intensity of statin therapy on diabetes risk. They examined data from 32,752 participants without diabetes at baseline in five randomized controlled trials with more than 1,000 participants and more than 1 year of follow-up, comparing high-dose therapy against moderate-dose statin therapy.21,22,26–28 New diabetes was considered present if there was an adverse event report of diabetes, if glucose-lowering drugs were started, or if two fasting plasma glucose measurements were higher than 7 mmol/L (126 mg/dL).
Diabetes developed in 1,449 (8.8%) of the intensive-therapy group and 1,300 (8.0%) of the moderate-therapy group (OR 1.12, 95% CI 1.04–1.22). In contrast, incident cardiovascular disease occurred in 3,134 (19.1%) of the intensive-therapy group and 3,550 (21.7%) of the moderate-therapy group (OR 0.84, 95% CI 0.75–0.94). Therefore, there was an 0.8% absolute increase in diabetes cases on high-dose statins and a 2.6% absolute reduction in adverse cardiovascular events.
CAUTION IN INTERPRETING THESE DATA
There are many reasons for caution in interpreting these studies.
The trials were not designed to look for diabetes
The data supporting the relationship between statin therapy and higher risk of diabetes are primarily from observational studies. These studies were not prospectively designed to address this question, and we therefore need to view this as association and not as causation.
The definition of diabetes varied between trials, and new-onset diabetes was often not rigorously screened for. In many trials the outcome of diabetes was at least partially based on nonstandardized, nonadjudicated physician reporting.
Consequently, if statins reduce the risk of diabetes, the results from WOSCOPS may overstate the reduction, since this study used a non-standard definition of incident diabetes (fasting plasma glucose > 126 mg/dL plus a > 36 mg/dL increase from baseline). When Sattar et al11 reanalyzed WOSCOPS data using a more standard definition, they found a smaller effect.
On the other hand, nonstandardized physician reporting may overstate an adverse effect. Sattar et al11 also found that when fasting plasma glucose levels alone were used as the definition for diabetes, the overall risk was attenuated and was no longer statistically significant (OR 1.07, 95% CI 0.97–1.17).
Perhaps statin therapy uncovers diabetes only in people at risk of diabetes
Perhaps statin therapy uncovers diabetes only in people at higher baseline risk of developing diabetes. Therefore, this adverse effect may be restricted to certain groups and not applicable to the general population.
In JUPITER, one of the two trials in which, on independent analysis, statin use was associated with new diabetes, 77% of patients in the rosuvastatin group who developed diabetes had impaired fasting glucose at entry and therefore were at higher risk of developing diabetes.6
Possibly, the relationship is driven by preexisting metabolic syndrome or other risk factors for diabetes. In the two studies that reported a statistically significantly higher incidence of new diabetes, more than 40% of patients in JUPITER met the criteria for metabolic syndrome, and metabolic syndrome, which increases in prevalence with age, was likely more prominent in the elderly population in PROSPER.
Waters et al23 grouped patients according to whether they had risk factors for diabetes (impaired fasting glucose, obesity, elevated triglycerides, and hypertension) and found that those who had none or one of these risk factors had no difference in the rate of new-onset diabetes with either moderate or intensive statin therapy, but the risk was pronounced in those who had three or four risk factors.
Ridker et al29 reanalyzed the JUPITER data from patients who did not have cardiovascular disease at baseline. Overall, for every 54 new cases of diabetes in follow-up, 134 cardiovascular events or deaths were prevented. In subgroup analysis, those who had one or more risk factors for diabetes at baseline (metabolic syndrome, impaired fasting glucose, obesity, or hemoglobin A1c > 6%) had a 39% reduction in the primary end point and a 28% increase in new diabetes. Those who had none of these risk factors had a 52% lower rate of cardiovascular events but no increase in diabetes.
Other confounding factors
Bias and confounding factors are difficult to control for in studies without prospectively defined, recognized, and analyzed outcomes.
Although it may be a bit of a stretch, residual confounding factors such as myalgia side effects while on statins may reduce exercise in the statin-treatment groups. Perhaps a change to a healthier lifestyle after cardiovascular events may be more common in placebo groups. Improved survival with statins may allow more people at risk of diabetes to live longer and present with the diagnosis.30
POSSIBLE EXPLANATIONS, BUT NO UNIFYING MECHANISM
If mechanisms could be identified to explain the association between statins and diabetes, this would strengthen the argument that it is a cause-and-effect relationship. Many explanations have been proposed as to how statins may influence glucose metabolism and insulin sensitivity.31–34 These are possible explanations based on other observations.
In theory, statins may improve insulin sensitivity via their anti-inflammatory effect, since inflammatory markers and proinflammatory cytokines have been linked with insulin resistance. However, other effects of statins may adversely affect glycemic control.
In vivo analysis has shown that some but not all statins increase insulin levels and decrease insulin sensitivity in a dose-dependent fashion. Some statins decrease adiponectin and may worsen glycemic control through loss of adiponectin’s proposed protective anti-proliferative and antiangiogenic properties. In vitro studies and animal studies have demonstrated a decrease in expression of insulin-responsive glucose transporter 4 (GLUT4) with atorvastatin, and an increase in GLUT1. It has been hypothesized that reduction in isoprenoid biosynthesis or decreased insulin signaling may explain these effects and that changes in glucose transport in adipocytes may cause insulin resistance. Other studies suggest that dysregulation of cellular cholesterol may attenuate beta-cell function. Impaired biosynthesis of ubiquinones may result in delayed production of adenosine triphosphate and consequently diminish insulin release.
But different effects have been reported for atorvastatin, simvastatin, and pravastatin, arguing against a unifying explanation or, alternatively, suggesting that differences in lipophilicity and potency among statins are important. Hydrophilic statins may be less likely to be taken up by extrahepatic cells such as pancreatic cells and adipocytes, possibly lessening these effects. However, the strong association between rosuvastatin (which is hydrophilic) and new diabetes would not support this hypothesis.
Despite these speculations, lack of conformity in response to different statins and discrepancies in the clinical outcomes noted in trials fail to clearly identify a common causative mechanism.
OTHER COMMON THERAPIES MAY INFLUENCE GLYCEMIC CONTROL
Statins are not the first drugs for reducing cardiovascular risk that have been shown to affect glucose levels during treatment.
Niacin
Niacin has been known to increase glucose levels but has long been used as a treatment for dyslipidemia despite this caution. Reduced glycemic control during niacin treatment in diabetic patients does not seem to alter the beneficial effects of treatment.35–37
In a post hoc analysis of the Coronary Drug Project (CDP), in patient subgroups defined by baseline fasting plasma glucose and compared with placebo, niacin reduced the 6-year risk of recurrent myocardial infarction and the combined end point of coronary heart disease death or nonfatal myocardial infarction similarly (interactive P value nonsignificant) across all levels of baseline fasting plasma glucose, including levels of 126 mg/dL or higher at study entry.36
In another post hoc analysis of CDP patient subgroups defined by the change in glycemic status from baseline to 1 year, niacin reduced the 6-year risk of the same end points similarly (interactive P value nonsignificant) across all levels of change in fasting plasma glucose from baseline to year 1, whether baseline fasting plasma glucose levels decreased, stayed the same, or increased to 10 mg/dL or higher on niacin therapy.36
Therefore, the beneficial effect of niacin of reducing the rate of recurrent nonfatal myocardial infarction and coronary heart disease events was not significantly diminished when impaired fasting glucose or diabetes was present when therapy was started or by on-therapy increases from baseline fasting plasma glucose.
In addition, on-therapy changes in glycemic control may be dose-related and minimized by surveillance and therapy adjustments. The Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial (ADVENT)38 found that changes in glycemic control were minimal as measured by fasting glucose and hemoglobin A1c; were associated with a higher niacin dose (1.5 g/day vs 1 g/day); and, when present, were successfully managed by adjusting the diabetes treatment regimen.
Antihypertensive drugs
Diuretics as well as beta-blockers have been reported to increase the incidence of diabetes in patients with hypertension.15,38–40
A retrospective longitudinal cohort study40 in 2009 examined the development of new-onset diabetes (defined as a new ICD-9 code for diabetes or initiation of diabetes treatment) in 24,688 treated hypertensive patients without diabetes at baseline; 4,385 (17.8%) of the patients developed diabetes. After adjusting for sex and age, the risk of new diabetes was significant in users of diuretics (OR 1.10), beta-blockers (OR 1.12), and calcium channel blockers (OR 1.10) compared with users of angiotensin-converting enzyme inhibitors, (OR 0.92), angiotensin receptor blockers (OR 0.90), or alpha-blockers (OR 0.88).
However, the increase in blood glucose does not seem to attenuate the beneficial effects of reducing cardiovascular events. In the Antihypertensive and Lipid-lowering Treatment to Prevent Heart Attack Trial (ALLHAT),15 a long-term follow-up of those developing new-onset diabetes while taking chlorthalidone (Hygroton) found no difference in the risk of death from cardiovascular disease or from any cause (hazard ratio = 1.04).15
CLINICAL IMPLICATIONS
Balancing the benefits and risks of statins
It is important to examine how the 0.4% increase in absolute risk of new-onset diabetes as calculated in meta-analyses compares with the benefits of statin treatment in terms of cardiovascular risk reduction.
Using data from the Cholesterol Treatment Trialists (CTT) meta-analysis of statin trials in 71,370 participants, Sattar et al11 estimated that statin treatment is associated with 5.4 fewer deaths from coronary heart disease and cases of nonfatal myocardial infarction per 255 patients treated over 4 years for each 1-mmol/L (39 mg/dL) reduction in LDL-C compared with controls. The benefit would be even greater if stroke, revascularization, and hospitalization are included as end points. This benefit is contrasted with the risk of developing 1 additional case of diabetes for every 255 patients treated with statins over the same period.
Preiss et al25 calculated that there were 2 more cases of diabetes per 1,000 patient-years in patients receiving intensive doses than in those receiving moderate doses (18.9 vs 16.9), corresponding to 1 additional case of diabetes for every 498 patients treated per year. However, there were 6.5 fewer first major cardiovascular events per 1,000 patient-years (44.5 vs 51.0), corresponding to a number needed to treat per year to prevent 1 cardiovascular event of 155. Most of the benefit was due to fewer revascularizations, followed by nonfatal myocardial infarctions. The 12% increase in new diabetes with high-dose therapy contrasted with a 16% reduction in new cardiovascular disease combined events (OR 0.84, 95% CI 0.75–0.94).
As previously noted, in the JUPITER trial, the benefits of preventing cardiovascular events with statin therapy outweighed the risk of new diabetes in people both with and without baseline risk factors for diabetes.29 Similar to the observations with niacin and some antihypertensive drugs, the increase in blood glucose with statins does not appear to reduce the benefits of cardiovascular risk reduction in these patients at moderate to high risk, even when used at high doses.
People with diabetes need aggressive lipid-lowering—with statins
Diabetes is a coronary heart disease risk equivalent and is associated with high risk of cardiovascular events.41–46 Overall, the risk for these adverse events is two to four times greater in people with diabetes than without. Atherosclerosis-related events account for approximately 65% to 75% of all deaths in people with diabetes, and 75% of these events are coronary. Lipid abnormalities are strongly correlated with the risk of cardiovascular disease in people with diabetes, and aggressive treatment of risk factors, particularly lipid abnormalities, has been shown to reduce this risk.47–49 And data from multiple clinical trials support the use of statins to lower LDL-C as the first-line therapy for dyslipidemia in people with diabetes, just as it is in the general population.3–7,9,13,23,50–61
Analyses of diabetic subgroups encompassing 18,000 to 20,000 patients in the large statin trials have clearly demonstrated the benefits of statin therapy. A recent metaanalysis of 10 placebo-controlled trials that included approximately 16,000 patients with diabetes and 54,000 without diabetes demonstrated a 30% reduction in coronary heart disease, a 19% reduction in strokes, and a 12% reduction in mortality.54 Furthermore, in another meta-analysis of 14 trials, a similar 22% reduction in coronary heart disease was noted in people with diabetes whether or not they had a history of cardiovascular disease.55
Therefore, aggressive treatment of lipid abnormalities with statins as primary treatment has generally been adopted as a standard of care in diabetic patients, particularly those with clinical cardiovascular disease or one or more risk factors. The Adult Treatment Panel III guidelines recommend a minimum LDL-C goal of less than 100 mg/dL and a goal of less than 70 mg/dL as an option for patients with diabetes (Table 1).41,62 Similar recommendations have been issued by the American Diabetes Association together with the American College of Cardiology (Table 2),30 the American Diabetes Association by itself,63 and the American Academy of Pediatrics.6
Is new-onset diabetes as dangerous as established diabetes?
In studies to date, there did not appear to be more events in those who developed new-onset diabetes.
Waters et al,24 evaluating three trials of high-dose atorvastatin therapy, found that major cardiovascular events occurred in 11.3% of those with new-onset diabetes, 10.8% of those without new-onset diabetes (HR 1.02, 95% CI 0.77–1.35), and 17.5% of those who had diabetes at baseline.
Therefore, it may not be appropriate to extrapolate the glucose changes seen on statin therapy to an equivalent increase in adverse cardiovascular events as seen in other diabetic patients. The beneficial reduction in cardiovascular events does not appear to be diminished in those developing diabetes. It is not clear that the increase in glucose on statins has the same implications of a new diagnosis of diabetes. Does this elevation in glucose represent true diabetes or some downstream effect? For example, thiazide diuretics have been known to increase blood glucose levels, but the levels drop when these drugs are discontinued, even after many years of treatment.
On the other hand, it is possible that follow-up of 5 years or less in clinical trials has not allowed sufficient time to examine the influence of the increase in new-onset diabetes on future cardiovascular events. In addition, because of the widespread use of statins across a broad range of cardiovascular risk, even if the effect is small in absolute terms, the potential adverse effects are magnified, particularly in a low-risk population in which the cardiovascular benefits are smaller.
The association is real, but questions remain
In view of the evidence, it is difficult to refute that an association exits between statin use and new-onset diabetes, at least in some subgroups. The dose response noted in some studies further reinforces the conclusion that the association is real. However, many questions remain unanswered regarding mechanism of effect, whether there are differences depending on the particular statin or dose used, or differential effects in the populations treated (such as patients with metabolic syndrome or the elderly).
Until the contradictory observations can be resolved and plausible mechanisms of action elucidated, causality cannot be established. From a clinical standpoint there is no current evidence suggesting that the elevations in blood glucose seen while on lipid-lowering or blood-pressure-lowering therapy are associated with an increased risk of cardiovascular events or that they attenuate the beneficial effects of the therapy.
Statins should continue to be used in patients at high risk
Until further studies are done, statins should continue to be used, after assessing the risks and the benefits.
Primary prevention patients at moderate to high risk and secondary prevention patients stand to gain from statin therapy, and it should not be denied or doses reduced on the basis of concerns about the development of new-onset diabetes. The recognized modest risk of developing diabetes does not appear to blunt the cardioprotective effects of statin therapy in these moderate-to high-risk groups.
Rather than stop statins in patients at risk of diabetes such as the elderly or those with prediabetes, insulin resistance, or metabolic syndrome who are on therapy for appropriate reasons, it is reasonable to continue these drugs, monitoring glucose more closely and emphasizing the importance of weight reduction, diet, and aerobic exercise for preventing diabetes. The Diabetes Prevention Program Research Group, for example, reduced the incidence of diabetes by 58% over 2.8 years of follow-up with intensive lifestyle interventions (a low-calorie, low-fat diet plus moderate physical activity 150 minutes per week) vs usual care in at-risk populations.65
Should statins be used more cautiously in patients at lower risk?
The most recent Cholesterol Treatment Trialists meta-analysis of 27 randomized clinical trials (22 placebo-controlled, 134,537 people; 5 high-dose vs low-dose, 39,612 people) reported that reducing LDL-C with statins lowered cardiovascular risk even in low-risk patients.66 Overall, there were 21% fewer major cardiovascular events (coronary heart disease, stroke, or coronary revascularization) for every 1-mmol/L reduction in LDL-C.
The proportional reduction in events was at least as large in the two lowest-risk groups (estimated 5-year risk of < 5% and 5% to < 10%, 53,152 people) as in the higher-risk groups. This was reflected mainly in fewer nonfatal myocardial infarctions and coronary revascularizations. In these groups, the absolute reduction in risk for each 1-mmol/L reduction in LDL-C was 11 per 1,000 patients over 5 years. Even in this low-risk population, the reduction in cardiovascular risk seems to compare favorably with the small estimated increase risk of diabetes.
However, even in the lowest-risk group studied, the average baseline LDL-C level was greater than 130 mg/dL.
Therefore, in groups in which the benefits of statins on cardiovascular risk reduction are less robust (eg, low-risk primary prevention groups without significant elevations in LDLC, particularly the elderly), it would not be difficult to justify the case for more cautious use of statin therapy. If statins are used in these low-risk groups, restricting their use to those with at least moderate LDL-C elevation, using less aggressive LDL-C-lowering targets, and regular monitoring of fasting glucose seem reasonable until further information is available.
On february 28, 2012, the US Food and Drug Administration (FDA) updated its labeling requirements for statins. In addition to revising its recommendations for monitoring liver function and its alerts about reports of memory loss, the FDA also warned of the possibility of new-onset diabetes mellitus and worse glycemic control in patients taking statin drugs.1
This change stoked an ongoing debate about the risk of diabetes with statin use and the implications of such an effect. To understand the clinical consequences of this alert and its effect on treatment decisions, we need to consider the degree to which statins lower the risk of cardiovascular disease in patients at high risk (including diabetic patients), the magnitude of the risk of developing new diabetes while on statin therapy, and the ratio of risk to benefit in treated populations.
This review will discuss the evidence for this possible adverse effect and the implications for clinical practice.
DO STATINS CAUSE DIABETES?
Individual controlled trials dating back more than a decade have had conflicting results about new diabetes and poorer diabetic control in patients taking statins.
The West of Scotland Coronary Prevention Study (WOSCOPS)2 suggested that the incidence of diabetes was 30% lower in patients taking pravastatin (Pravachol) 40 mg/day than with placebo. However, this was not observed with atorvastatin (Lipitor) 10 mg/day in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid-Lowering Arm (ASCOT-LLA)3 in hypertensive patients or in the Collaborative Atorvastatin Diabetes Study (CARDS)4 in diabetic patients,4 nor was it noted with simvastatin (Zocor) 40 mg/day in the Heart Protection Study (HPS).5
The Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER),6 using the more potent agent rosuvastatin (Crestor) 20 mg/day in patients with elevated levels of C-reactive protein (CRP), was stopped early when an interim analysis found a 44% lower incidence of the primary end point. However, the trial also reported a 26% higher incidence of diabetes in follow-up of less than 2 years.
In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER),7 with a mean age at entry of 75, there was a 32% higher incidence of diabetes with pravastatin therapy.7
Results of meta-analyses
Several meta-analyses have addressed these differences.
Rajpathak et al8 performed a meta-analysis, published in 2009, of six trials—WOSCOPS,2 ASCOT-LLA,3 JUPITER,6 HPS,5 the Long-term Intervention With Pravastatin in Ischaemic Disease (LIPID) study,9 and the Controlled Rosuvastatin Multinational Study in Heart Failure (CORONA),10 with a total of 57,593 patients. They calculated that the incidence of diabetes was 13% higher (an absolute difference of 0.5%) in statin recipients, which was statistically significant. In their initial analysis, the authors excluded WOSCOPS, describing it as hypothesis-generating. The relative increase in risk was less—6%—and was not statistically significant when WOSCOPS was included.
Sattar et al,11 in a larger meta-analysis published in 2010, included 91,140 participants in 13 major statin trials conducted between 1994 and 2009; each trial had more than 1,000 patients and more than 1 year of follow-up.2,3,5–7,9,10,12–17 New diabetes was defined as physician reporting of new diabetes, new diabetic medication use, or a fasting glucose greater than 7 mmol/L (126 mg/dL).
New diabetes occurred in 2,226 (4.89%) of the statin recipients and in 2,052 (4.5%) of the placebo recipients, an absolute difference of 0.39%, or 9% more (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.02–1.17) (Figure 1).
The incidence of diabetes varied substantially among the 13 trials, with only JUPITER6 and PROSPER7 finding statistically significant increases in rates (26% and 32%, respectively). Of the other 11 trials, 4 had nonsignificant trends toward lower incidence,2,9,13,17 while the 7 others had nonsignificant trends toward higher incidence.
Does the specific statin make a difference?
Questions have been raised as to whether the type of statin used, the intensity of therapy, or the population studied contributed to these differences. Various studies suggest that factors such as using hydrophilic vs lipophilic statins (hydrophilic statins include pravastatin and rosuvastatin; lipophilic statins include atorvastatin, lovastatin, and simvastatin), the dose, the extent of lowering of low-density lipoprotein cholesterol (LDL-C), and the age or clinical characteristics of the population studied may influence this relationship.18–20
Yamakawa et al18 examined the effect of atorvastatin 10 mg/day, pravastatin 10 mg/day, and pitavastatin (Livalo) 2 mg/day on glycemic control over 3 months in a retrospective analysis. Random blood glucose and hemoglobin A1c levels were increased in the atorvastatin group but not in the other two.18
A prospective comparison of atorvastatin 20 mg vs pitavastatin 4 mg in patients with type 2 diabetes, presented at the American College of Cardiology’s 2011 annual meeting, reported a significant increase in fasting glucose levels with atorvastatin, particularly in women, but not with pitavastatin.19
In the Compare the Effect of Rosuvastatin With Atorvastatin on Apo B/Apo A-1 Ratio in Patients With Type 2 Diabetes Mellitus and Dyslipidaemia (CORALL) study,20 both high-dose rosuvastatin (40 mg) and high-dose atorvastatin (80 mg) were associated with significant increases in hemoglobin A1c, although the mean fasting glucose levels were not significantly different at 18 weeks of therapy.
A meta-analysis by Sattar et al11 did not find a clear difference between lipophilic statins (OR 1.10 vs placebo) and hydrophilic statins (OR 1.08). In analysis by statin type, the combined rosuvastatin trials were statistically significant in favor of a higher diabetes risk (OR 1.18, 95% CI 1.04–1.44). Nonsignificant trends were noted for atorvastatin trials (OR 1.14) and simvastatin trials (OR 1.11) and less so for pravastatin (OR 1.03); the OR for lovastatin was 0.98. This may suggest that there is a stronger effect with more potent statins or with greater lowering of LDL-C.
Meta-regression analysis in this study demonstrated that diabetes risk with statins was higher in older patients but was not influenced by body mass index or by the extent that LDL-C was lowered.
Statin dose as a risk factor
Intensive-dose statin therapy has been shown to reduce cardiovascular risk more than low-dose or moderate-dose therapy, thus supporting more aggressive treatment of LDL-C in higher-risk patients. However, some controlled studies comparing more-potent with less-potent statin regimens suggest that there may also be a higher risk of incident diabetes at higher doses.21–24
In a post hoc analysis of the Pravastatin or Atorvastatin Evaluation and Infection Therapy– Thrombolysis in Myocardial Infarction 22 (PROVE-IT TIMI 22) trial,21 patients who had experienced an acute coronary syndrome had a greater increase in hemoglobin A1c if treated with atorvastatin 80 mg/day than with pravastatin 40 mg/day.
Waters et al23 reported a higher risk of new diabetes with atorvastatin 80 mg than with placebo and a trend toward a higher risk with atorvastatin 80 mg than with atorvastatin 10 mg or simvastatin 20 mg.
In contrast, a review by Yousef et al24 of the data from the Enhanced Feedback for Effective Cardiac Treatment (EFFECT) study did not find a higher diabetes risk with more intensive statin therapy based on the magnitude of LDL-C reduction. A propensity-matched examination of deaths, recurrent acute ischemic events, or new diabetes in patients previously hospitalized with myocardial infarction found no differences in these end points each year out to 5 years. The risk of diabetes was in fact lower (but the difference was not statistically significant) in the high-dose groups out to 5 years. The risk of myocardial infarction or death was numerically different in the high-dose groups, but the difference was not statistically significant.
Preiss et al25 in 2011 performed a meta-analysis of the impact of intensity of statin therapy on diabetes risk. They examined data from 32,752 participants without diabetes at baseline in five randomized controlled trials with more than 1,000 participants and more than 1 year of follow-up, comparing high-dose therapy against moderate-dose statin therapy.21,22,26–28 New diabetes was considered present if there was an adverse event report of diabetes, if glucose-lowering drugs were started, or if two fasting plasma glucose measurements were higher than 7 mmol/L (126 mg/dL).
Diabetes developed in 1,449 (8.8%) of the intensive-therapy group and 1,300 (8.0%) of the moderate-therapy group (OR 1.12, 95% CI 1.04–1.22). In contrast, incident cardiovascular disease occurred in 3,134 (19.1%) of the intensive-therapy group and 3,550 (21.7%) of the moderate-therapy group (OR 0.84, 95% CI 0.75–0.94). Therefore, there was an 0.8% absolute increase in diabetes cases on high-dose statins and a 2.6% absolute reduction in adverse cardiovascular events.
CAUTION IN INTERPRETING THESE DATA
There are many reasons for caution in interpreting these studies.
The trials were not designed to look for diabetes
The data supporting the relationship between statin therapy and higher risk of diabetes are primarily from observational studies. These studies were not prospectively designed to address this question, and we therefore need to view this as association and not as causation.
The definition of diabetes varied between trials, and new-onset diabetes was often not rigorously screened for. In many trials the outcome of diabetes was at least partially based on nonstandardized, nonadjudicated physician reporting.
Consequently, if statins reduce the risk of diabetes, the results from WOSCOPS may overstate the reduction, since this study used a non-standard definition of incident diabetes (fasting plasma glucose > 126 mg/dL plus a > 36 mg/dL increase from baseline). When Sattar et al11 reanalyzed WOSCOPS data using a more standard definition, they found a smaller effect.
On the other hand, nonstandardized physician reporting may overstate an adverse effect. Sattar et al11 also found that when fasting plasma glucose levels alone were used as the definition for diabetes, the overall risk was attenuated and was no longer statistically significant (OR 1.07, 95% CI 0.97–1.17).
Perhaps statin therapy uncovers diabetes only in people at risk of diabetes
Perhaps statin therapy uncovers diabetes only in people at higher baseline risk of developing diabetes. Therefore, this adverse effect may be restricted to certain groups and not applicable to the general population.
In JUPITER, one of the two trials in which, on independent analysis, statin use was associated with new diabetes, 77% of patients in the rosuvastatin group who developed diabetes had impaired fasting glucose at entry and therefore were at higher risk of developing diabetes.6
Possibly, the relationship is driven by preexisting metabolic syndrome or other risk factors for diabetes. In the two studies that reported a statistically significantly higher incidence of new diabetes, more than 40% of patients in JUPITER met the criteria for metabolic syndrome, and metabolic syndrome, which increases in prevalence with age, was likely more prominent in the elderly population in PROSPER.
Waters et al23 grouped patients according to whether they had risk factors for diabetes (impaired fasting glucose, obesity, elevated triglycerides, and hypertension) and found that those who had none or one of these risk factors had no difference in the rate of new-onset diabetes with either moderate or intensive statin therapy, but the risk was pronounced in those who had three or four risk factors.
Ridker et al29 reanalyzed the JUPITER data from patients who did not have cardiovascular disease at baseline. Overall, for every 54 new cases of diabetes in follow-up, 134 cardiovascular events or deaths were prevented. In subgroup analysis, those who had one or more risk factors for diabetes at baseline (metabolic syndrome, impaired fasting glucose, obesity, or hemoglobin A1c > 6%) had a 39% reduction in the primary end point and a 28% increase in new diabetes. Those who had none of these risk factors had a 52% lower rate of cardiovascular events but no increase in diabetes.
Other confounding factors
Bias and confounding factors are difficult to control for in studies without prospectively defined, recognized, and analyzed outcomes.
Although it may be a bit of a stretch, residual confounding factors such as myalgia side effects while on statins may reduce exercise in the statin-treatment groups. Perhaps a change to a healthier lifestyle after cardiovascular events may be more common in placebo groups. Improved survival with statins may allow more people at risk of diabetes to live longer and present with the diagnosis.30
POSSIBLE EXPLANATIONS, BUT NO UNIFYING MECHANISM
If mechanisms could be identified to explain the association between statins and diabetes, this would strengthen the argument that it is a cause-and-effect relationship. Many explanations have been proposed as to how statins may influence glucose metabolism and insulin sensitivity.31–34 These are possible explanations based on other observations.
In theory, statins may improve insulin sensitivity via their anti-inflammatory effect, since inflammatory markers and proinflammatory cytokines have been linked with insulin resistance. However, other effects of statins may adversely affect glycemic control.
In vivo analysis has shown that some but not all statins increase insulin levels and decrease insulin sensitivity in a dose-dependent fashion. Some statins decrease adiponectin and may worsen glycemic control through loss of adiponectin’s proposed protective anti-proliferative and antiangiogenic properties. In vitro studies and animal studies have demonstrated a decrease in expression of insulin-responsive glucose transporter 4 (GLUT4) with atorvastatin, and an increase in GLUT1. It has been hypothesized that reduction in isoprenoid biosynthesis or decreased insulin signaling may explain these effects and that changes in glucose transport in adipocytes may cause insulin resistance. Other studies suggest that dysregulation of cellular cholesterol may attenuate beta-cell function. Impaired biosynthesis of ubiquinones may result in delayed production of adenosine triphosphate and consequently diminish insulin release.
But different effects have been reported for atorvastatin, simvastatin, and pravastatin, arguing against a unifying explanation or, alternatively, suggesting that differences in lipophilicity and potency among statins are important. Hydrophilic statins may be less likely to be taken up by extrahepatic cells such as pancreatic cells and adipocytes, possibly lessening these effects. However, the strong association between rosuvastatin (which is hydrophilic) and new diabetes would not support this hypothesis.
Despite these speculations, lack of conformity in response to different statins and discrepancies in the clinical outcomes noted in trials fail to clearly identify a common causative mechanism.
OTHER COMMON THERAPIES MAY INFLUENCE GLYCEMIC CONTROL
Statins are not the first drugs for reducing cardiovascular risk that have been shown to affect glucose levels during treatment.
Niacin
Niacin has been known to increase glucose levels but has long been used as a treatment for dyslipidemia despite this caution. Reduced glycemic control during niacin treatment in diabetic patients does not seem to alter the beneficial effects of treatment.35–37
In a post hoc analysis of the Coronary Drug Project (CDP), in patient subgroups defined by baseline fasting plasma glucose and compared with placebo, niacin reduced the 6-year risk of recurrent myocardial infarction and the combined end point of coronary heart disease death or nonfatal myocardial infarction similarly (interactive P value nonsignificant) across all levels of baseline fasting plasma glucose, including levels of 126 mg/dL or higher at study entry.36
In another post hoc analysis of CDP patient subgroups defined by the change in glycemic status from baseline to 1 year, niacin reduced the 6-year risk of the same end points similarly (interactive P value nonsignificant) across all levels of change in fasting plasma glucose from baseline to year 1, whether baseline fasting plasma glucose levels decreased, stayed the same, or increased to 10 mg/dL or higher on niacin therapy.36
Therefore, the beneficial effect of niacin of reducing the rate of recurrent nonfatal myocardial infarction and coronary heart disease events was not significantly diminished when impaired fasting glucose or diabetes was present when therapy was started or by on-therapy increases from baseline fasting plasma glucose.
In addition, on-therapy changes in glycemic control may be dose-related and minimized by surveillance and therapy adjustments. The Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial (ADVENT)38 found that changes in glycemic control were minimal as measured by fasting glucose and hemoglobin A1c; were associated with a higher niacin dose (1.5 g/day vs 1 g/day); and, when present, were successfully managed by adjusting the diabetes treatment regimen.
Antihypertensive drugs
Diuretics as well as beta-blockers have been reported to increase the incidence of diabetes in patients with hypertension.15,38–40
A retrospective longitudinal cohort study40 in 2009 examined the development of new-onset diabetes (defined as a new ICD-9 code for diabetes or initiation of diabetes treatment) in 24,688 treated hypertensive patients without diabetes at baseline; 4,385 (17.8%) of the patients developed diabetes. After adjusting for sex and age, the risk of new diabetes was significant in users of diuretics (OR 1.10), beta-blockers (OR 1.12), and calcium channel blockers (OR 1.10) compared with users of angiotensin-converting enzyme inhibitors, (OR 0.92), angiotensin receptor blockers (OR 0.90), or alpha-blockers (OR 0.88).
However, the increase in blood glucose does not seem to attenuate the beneficial effects of reducing cardiovascular events. In the Antihypertensive and Lipid-lowering Treatment to Prevent Heart Attack Trial (ALLHAT),15 a long-term follow-up of those developing new-onset diabetes while taking chlorthalidone (Hygroton) found no difference in the risk of death from cardiovascular disease or from any cause (hazard ratio = 1.04).15
CLINICAL IMPLICATIONS
Balancing the benefits and risks of statins
It is important to examine how the 0.4% increase in absolute risk of new-onset diabetes as calculated in meta-analyses compares with the benefits of statin treatment in terms of cardiovascular risk reduction.
Using data from the Cholesterol Treatment Trialists (CTT) meta-analysis of statin trials in 71,370 participants, Sattar et al11 estimated that statin treatment is associated with 5.4 fewer deaths from coronary heart disease and cases of nonfatal myocardial infarction per 255 patients treated over 4 years for each 1-mmol/L (39 mg/dL) reduction in LDL-C compared with controls. The benefit would be even greater if stroke, revascularization, and hospitalization are included as end points. This benefit is contrasted with the risk of developing 1 additional case of diabetes for every 255 patients treated with statins over the same period.
Preiss et al25 calculated that there were 2 more cases of diabetes per 1,000 patient-years in patients receiving intensive doses than in those receiving moderate doses (18.9 vs 16.9), corresponding to 1 additional case of diabetes for every 498 patients treated per year. However, there were 6.5 fewer first major cardiovascular events per 1,000 patient-years (44.5 vs 51.0), corresponding to a number needed to treat per year to prevent 1 cardiovascular event of 155. Most of the benefit was due to fewer revascularizations, followed by nonfatal myocardial infarctions. The 12% increase in new diabetes with high-dose therapy contrasted with a 16% reduction in new cardiovascular disease combined events (OR 0.84, 95% CI 0.75–0.94).
As previously noted, in the JUPITER trial, the benefits of preventing cardiovascular events with statin therapy outweighed the risk of new diabetes in people both with and without baseline risk factors for diabetes.29 Similar to the observations with niacin and some antihypertensive drugs, the increase in blood glucose with statins does not appear to reduce the benefits of cardiovascular risk reduction in these patients at moderate to high risk, even when used at high doses.
People with diabetes need aggressive lipid-lowering—with statins
Diabetes is a coronary heart disease risk equivalent and is associated with high risk of cardiovascular events.41–46 Overall, the risk for these adverse events is two to four times greater in people with diabetes than without. Atherosclerosis-related events account for approximately 65% to 75% of all deaths in people with diabetes, and 75% of these events are coronary. Lipid abnormalities are strongly correlated with the risk of cardiovascular disease in people with diabetes, and aggressive treatment of risk factors, particularly lipid abnormalities, has been shown to reduce this risk.47–49 And data from multiple clinical trials support the use of statins to lower LDL-C as the first-line therapy for dyslipidemia in people with diabetes, just as it is in the general population.3–7,9,13,23,50–61
Analyses of diabetic subgroups encompassing 18,000 to 20,000 patients in the large statin trials have clearly demonstrated the benefits of statin therapy. A recent metaanalysis of 10 placebo-controlled trials that included approximately 16,000 patients with diabetes and 54,000 without diabetes demonstrated a 30% reduction in coronary heart disease, a 19% reduction in strokes, and a 12% reduction in mortality.54 Furthermore, in another meta-analysis of 14 trials, a similar 22% reduction in coronary heart disease was noted in people with diabetes whether or not they had a history of cardiovascular disease.55
Therefore, aggressive treatment of lipid abnormalities with statins as primary treatment has generally been adopted as a standard of care in diabetic patients, particularly those with clinical cardiovascular disease or one or more risk factors. The Adult Treatment Panel III guidelines recommend a minimum LDL-C goal of less than 100 mg/dL and a goal of less than 70 mg/dL as an option for patients with diabetes (Table 1).41,62 Similar recommendations have been issued by the American Diabetes Association together with the American College of Cardiology (Table 2),30 the American Diabetes Association by itself,63 and the American Academy of Pediatrics.6
Is new-onset diabetes as dangerous as established diabetes?
In studies to date, there did not appear to be more events in those who developed new-onset diabetes.
Waters et al,24 evaluating three trials of high-dose atorvastatin therapy, found that major cardiovascular events occurred in 11.3% of those with new-onset diabetes, 10.8% of those without new-onset diabetes (HR 1.02, 95% CI 0.77–1.35), and 17.5% of those who had diabetes at baseline.
Therefore, it may not be appropriate to extrapolate the glucose changes seen on statin therapy to an equivalent increase in adverse cardiovascular events as seen in other diabetic patients. The beneficial reduction in cardiovascular events does not appear to be diminished in those developing diabetes. It is not clear that the increase in glucose on statins has the same implications of a new diagnosis of diabetes. Does this elevation in glucose represent true diabetes or some downstream effect? For example, thiazide diuretics have been known to increase blood glucose levels, but the levels drop when these drugs are discontinued, even after many years of treatment.
On the other hand, it is possible that follow-up of 5 years or less in clinical trials has not allowed sufficient time to examine the influence of the increase in new-onset diabetes on future cardiovascular events. In addition, because of the widespread use of statins across a broad range of cardiovascular risk, even if the effect is small in absolute terms, the potential adverse effects are magnified, particularly in a low-risk population in which the cardiovascular benefits are smaller.
The association is real, but questions remain
In view of the evidence, it is difficult to refute that an association exits between statin use and new-onset diabetes, at least in some subgroups. The dose response noted in some studies further reinforces the conclusion that the association is real. However, many questions remain unanswered regarding mechanism of effect, whether there are differences depending on the particular statin or dose used, or differential effects in the populations treated (such as patients with metabolic syndrome or the elderly).
Until the contradictory observations can be resolved and plausible mechanisms of action elucidated, causality cannot be established. From a clinical standpoint there is no current evidence suggesting that the elevations in blood glucose seen while on lipid-lowering or blood-pressure-lowering therapy are associated with an increased risk of cardiovascular events or that they attenuate the beneficial effects of the therapy.
Statins should continue to be used in patients at high risk
Until further studies are done, statins should continue to be used, after assessing the risks and the benefits.
Primary prevention patients at moderate to high risk and secondary prevention patients stand to gain from statin therapy, and it should not be denied or doses reduced on the basis of concerns about the development of new-onset diabetes. The recognized modest risk of developing diabetes does not appear to blunt the cardioprotective effects of statin therapy in these moderate-to high-risk groups.
Rather than stop statins in patients at risk of diabetes such as the elderly or those with prediabetes, insulin resistance, or metabolic syndrome who are on therapy for appropriate reasons, it is reasonable to continue these drugs, monitoring glucose more closely and emphasizing the importance of weight reduction, diet, and aerobic exercise for preventing diabetes. The Diabetes Prevention Program Research Group, for example, reduced the incidence of diabetes by 58% over 2.8 years of follow-up with intensive lifestyle interventions (a low-calorie, low-fat diet plus moderate physical activity 150 minutes per week) vs usual care in at-risk populations.65
Should statins be used more cautiously in patients at lower risk?
The most recent Cholesterol Treatment Trialists meta-analysis of 27 randomized clinical trials (22 placebo-controlled, 134,537 people; 5 high-dose vs low-dose, 39,612 people) reported that reducing LDL-C with statins lowered cardiovascular risk even in low-risk patients.66 Overall, there were 21% fewer major cardiovascular events (coronary heart disease, stroke, or coronary revascularization) for every 1-mmol/L reduction in LDL-C.
The proportional reduction in events was at least as large in the two lowest-risk groups (estimated 5-year risk of < 5% and 5% to < 10%, 53,152 people) as in the higher-risk groups. This was reflected mainly in fewer nonfatal myocardial infarctions and coronary revascularizations. In these groups, the absolute reduction in risk for each 1-mmol/L reduction in LDL-C was 11 per 1,000 patients over 5 years. Even in this low-risk population, the reduction in cardiovascular risk seems to compare favorably with the small estimated increase risk of diabetes.
However, even in the lowest-risk group studied, the average baseline LDL-C level was greater than 130 mg/dL.
Therefore, in groups in which the benefits of statins on cardiovascular risk reduction are less robust (eg, low-risk primary prevention groups without significant elevations in LDLC, particularly the elderly), it would not be difficult to justify the case for more cautious use of statin therapy. If statins are used in these low-risk groups, restricting their use to those with at least moderate LDL-C elevation, using less aggressive LDL-C-lowering targets, and regular monitoring of fasting glucose seem reasonable until further information is available.
- US Food and Drug Administration. Statin drugs—drug safety communication: class labeling change. February 28, 2012. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm293670.htm.
- Freeman DJ, Norrie J, Sattar N, et al. Pravastatin and the development of diabetes mellitus: evidence for a protective treatment effect in the West of Scotland Coronary Prevention Study. Circulation 2001; 103:357–362.
- Sever PS, Dahlof B, Poulter NR, et al; ASCOT investigators. Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-than-average cholesterol concentrations, in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid Lowering Arm (ASCOT-LLA): a multicentre randomised controlled trial. Lancet 2003; 361:1149–1158.
- Colhoun HM, Betteridge DJ, Durrington PN, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004; 364:685–696.
- Collins R, Armitage J, Parish S, Sleigh P, Peto R; for the Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol-lowering with simvastatin in 5963 people with diabetes: a randomised placebo-controlled trial. Lancet 2003; 361:2005–2016.
- Ridker PM, Danielson E, Fonseca FA, et al. Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein. N Engl J Med 2008; 359:2195–2207.
- Shepherd J, Blauw GJ, Murphy MB, et al; PROSPER Study Group. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002; 360:1623–1630.
- Rajpathak SN, Kumbhani DJ, Crandall J, Barzilai N, Alderman M, Ridker PM. Statin therapy and risk of developing type 2 diabetes: a meta-analysis. Diabetes Care 2009; 32:1924–1929.
- Keech A, Colquhoun D, Best J, et al. Secondary prevention of cardiovascular events with long-term pravastatin in patients with diabetes or impaired fasting glucose—results from the LIPID trial. Diabetes Care 2003; 26:2713–2721.
- Kjekshus J, Apetrei E, Barrios V, et al. Rosuvastatin in older patients with systolic heart failure. N Engl J Med 2007; 357:2248–2261.
- Sattar N, Preiss D, Murray HM, et al. Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials. Lancet 2010; 375:735–742.
- Nakamura H, Arakawa K, Itakura H, et al. Primary prevention of cardiovascular disease with pravastatin in Japan (MEGA Study): a prospective randomised controlled trial. Lancet 2006; 368:1155–1163.
- Downs JR, Clearfield M, Weis S, et al. Primary prevention of acute coronary events with lovastatin in men and women with average cholesterol levels: results of AFCAPS/TexCAPS. Air Force/Texas Coronary Atherosclerosis Prevention Study. JAMA 1998; 279:1615–1622.
- Scandinavian Simvastatin Survival Study study group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet 1994; 344:1383–1389.
- Barzilay JI, Davis BR, Pressel SL, et al; ALLHAT Collaborative Research Group. Long-term effects of incident diabetes mellitus on cardiovascular outcomes in people treated for hypertension: the ALLHAT Diabetes Extension Study. Circ Cardiovasc Qual Outcomes 2012; 5:153–162.
- Tavazzi L, Maggioni AP, Marchioli R, et al. Effect of rosuvastatin in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial. Lancet 2008; 372:1231–1239.
- GISSI Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico). Results of the low-dose (20 mg) pravastatin GISSI Prevenzione trial in 4271 patients with recent myocardial infarction: do stopped trials contribute to overall knowledge? Ital Heart J 2000; 1:810–820.
- Yamakawa T, Takano T, Tanaka S, Kadonosono K, Terauchi Y. Influence of pitavastatin on glucose tolerance in patients with type 2 diabetes mellitus. J Atheroscler Thromb 2008; 15:269–275.
- Kryzhanovski V, Gumprecht J, Zhu B, Yu CY, Hounslow N, Sponseller CA. Atorvastatin but not pitavastatin significantly increases fasting plasma glucose in patients with type 2 diabetes and combined dyslipidemia (abstract). J Am Coll Cardiol 2011; 57:E575.
- Simsek S, Schalkwijk CG, Wolffenbuttel BH. Effects of rosuvastatin and atorvastatin on glycaemic control in type 2 diabetes—the CORALL study. Diabet Med 2012; 29:628–631.
- Sabatine MS, Morrow DA, Giugliano RP, et al. Implications of upstream glycoprotein IIb/IIIa inhibition and coronary artery stenting in the invasive management of unstable angina/non-ST-elevation myocardial infarction: a comparison of the Thrombolysis In Myocardial Infarction (TIMI) IIIB trial and the Treat angina with Aggrastat and determine Cost of Therapy with Invasive or Conservative Strategy (TACTICS)-TIMI 18 trial. Circulation 2004; 110(suppl III):834–880.
- Shepherd J, Barter P, Carmena R, et al. Effect of lowering LDL cholesterol substantially below currently recommended levels in patients with coronary heart disease and diabetes: the Treating to New Targets (TNT) study. Diabetes Care 2006; 29:1220–1226.
- Waters DD, Ho JE, DeMicco DA, et al. Predictors of new-onset diabetes in patients treated with atorvastatin: results from 3 large randomized clinical trials. J Am Coll Cardiol 2011; 57:1535–1545.
- Yousef A, Tu JV, Wang J, Donovan L, Ko DT. The association of intensive statin therapy on long-term risks of cardiovascular events and diabetes following acute myocardial infarction (abstract). Circulation 2012; 125:e859.
- Preiss D, Seshasai SR, Welsh P, et al. Risk of incident diabetes with intensive-dose compared with moderate-dose statin therapy: a metaanalysis. JAMA 2011; 305:2556–2564.
- de Lemos JA, Blazing MA, Wiviott SD, et al; A to Z Investigators. Early intensive vs a delayed conservative simvastatin strategy in patients with acute coronary syndromes: phase Z of the A to Z trial. JAMA 2004; 292:1307–1316.
- Pedersen TR, Faegeman O, Kastelein JJ, et al; Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL) Study Group. High-dose atorvastatin vs usual-dose simvastatin for secondary prevention after myocardial infarction: the IDEAL study: a randomized controlled trial. JAMA 2005; 294:2437–2445.
- Armitage J, Bowman L, Wallendszus K, et al; Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH) Collaborative Group. Intensive lowering of LDL cholesterol with 80 mg versus 20 mg simvastatin daily in 12,064 survivors of myocardial infarction: a double-blind randomised trial. Lancet 2010; 37:1658–1669.
- Ridker PM, Pradhan A, MacFadyen JG, Libby P, Glynn RJ. Cardiovascular benefits and diabetes risks of statin therapy in primary prevention: an analysis from the JUPITER trial. Lancet 2012; 380:565–571.
- Brunzell JD, Davidson M, Furberg CD, et al; American Diabetes Association; American College of Cardiology Foundation. Lipoprotein management in patients with cardiometabolic risk: consensus statement from the American Diabetes Association and the American College of Cardiology Foundation. Diabetes Care 2008; 31:811–822.
- Koh KK, Quon MJ, Han SH, Lee Y, Kim SJ, Shin EK. Atorvastatin causes insulin resistance and increases ambient glycemia in hypercholesterolemic patients. J Am Coll Cardiol 2010; 55:1209–1216.
- Koh KK, Quon MJ, Han SH, et al. Differential metabolic effects of pravastatin and simvastatin in hypercholesterolemic patients. Atherosclerosis 2009; 204:483–490.
- Nakata M, Nagasaka S, Kusaka I, Matsuoka H, Ishibashi S, Yada T. Effects of statins on the adipocyte maturation and expression of glucose transporter 4 (SLC2A4): implications in glycaemic control. Diabetologia 2006; 49:1881–1892.
- Yada T, Nakata M, Shiraishi T, Kakei M. Inhibition by simvastatin, but not pravastatin, of glucose-induced cytosolic Ca2+ signalling and insulin secretion due to blockade of L-type Ca2+ channels in rat islet beta-cells. Br J Pharmacol 1999; 126:1205–1213.
- Guyton JR, Fazio S, Adewale AJ, et al. Effect of extended-release niacin on new-onset diabetes among hyperlipidemic patients treated with ezetimibe/simvastatin in a randomized controlled trial. Diabetes Care 2012; 35:857–860.
- Canner PL, Furberg CD, Terrin ML, McGovern ME. Benefits of niacin by glycemic status in patients with healed myocardial infarction (from the Coronary Drug Project). Am J Cardiol 2005; 95:254–257.
- Grundy SM, Vega GL, McGovern ME, et al; Diabetes Multicenter Research Group. Efficacy, safety, and tolerability of once-daily niacin for the treatment of dyslipidemia associated with type 2 diabetes: results of the Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial. Arch Intern Med 2002; 162:1568–1576.
- Gupta AK, Dahlof B, Dobson J, Sever PS, Wedel H, Poulter NRAnglo-Scandinavian Cardiac Outcomes Trial Investigators. Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial—Blood Pressure Lowering Arm and the relative influence of antihypertensive medication. Diabetes Care 2008; 31:982–988.
- Elliott WJ, Meyer PM. Incident diabetes in clinical trials of antihypertensive drugs: a network meta-analysis. Lancet 2007; 369:201–207.
- Jong JP, Chang MH, Tien L, et al. Antihypertensive drugs and new-onset diabetes: a retrospective longitudinal cohort study. Cardiovasc Ther 2009; 27:159–163.
- Third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation 2002; 106:3143–3421.
- Norhammar A, Tenerz A, Nilsson G, et al. Glucose metabolism in patients with acute myocardial infarction and no previous diagnosis of diabetes mellitus: a prospective study Lancet 2002; 359:2140–2144.
- Haffner SM, Lehto S, Ronnemaa T, Pyorala K, Laakso M. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med 1998; 339:229–234.
- Sprafka JM, Burke GL, Folsom AR, McGovbern PG, Hahn LP. Trends in prevalence of diabetes mellitus in patients with myocardial infarction and effect of diabetes on survival. The Minnesota Heart Survey. Diabetes Care 1991; 14:537–543.
- Geiss LS, Herman WH, Smith PJ. Mortality in non-insulin-dependent diabetes. In:Harris MI, Cowie CC, Stern MP, et al, editors. Diabetes in America. 2nd ed. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, 1995:233–257.
- Stamler J, Vaccaro O, Neaton JD, Wentworth D. Diabetes, other risk factors, and 12-yr cardiovascular mortality for men screened in the Multiple Risk Factor Intervention Trial. Diabetes Care 1993; 16:434–444.
- Turner RC, Millns H, Neil HA, et al. Risk factors for coronary artery disease in non-insulin dependent diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS: 23). BMJ 1998; 316:823–828.
- Gaede P, Vedel P, Larsen N, Jensen GV, Parving HH, Pedersen O. Multifactorial intervention and cardiovascular disease in patients with type 2 diabetes. N Engl J Med 2003; 348:383–393.
- Gaede P, Pederson O. Intensive integrated therapy of type 2 diabetes: implications for long-term prognosis. Diabetes 2004; 53:S39–S47.
- Goldberg RB, Mellies MJ, Sacks FM, et al. Cardiovascular events and their reduction with pravastatin in diabetic and glucose-intolerant myocardial infarction survivors with average cholesterol levels: subgroup analyses in the cholesterol and recurrent events (CARE) trial. The Care Investigators. Circulation 1998; 98:2513–2519.
- Pyðrälä K, Pedersen TR, Kjekshus J, Faergeman O, Olsson AG, Thorgeirsson G. Cholesterol lowering with simvastatin improves prognosis of diabetic patients with coronary heart disease. A subgroup analysis of the Scandinavian Simvastatin Survival Study (4S). Diabetes Care 1997; 20:614–620.
- Vijan S, Hayward RA; American College of Physicians. Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians. Ann Intern Med 2004; 140:650–658.
- Baigent C, Keech A, Kearney PM, et al; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005; 366:1267–1278. Errata in Lancet 2008; 371:2084, Lancet 2005; 366:1358.
- Brugts JJ, Yetgin T, Hoeks SE, et al. The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials. BMJ 2009; 338:b2376.
- Kearney PM, Blackwell L, Collins R, Keech A, Simes J, Baigent C; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis. Lancet 2008; 371:117–125.
- Nissen SE, Nicholls SJ, Sipahi I, et al; ASTEROID Investigators. Effect of very high-intensity statin therapy on regression of coronary atherosclerosis: the ASTEROID trial. JAMA 2006; 295:1556–1565.
- Cannon CP, Braunwald E, McCabe CH, et al; Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis in Myocardial Infarction 22 Investigators. Intensive versus moderate lipid lowering with statins after acute coronary syndromes et al. N Engl J Med 2004; 350:1495–1504.
- LaRosa JC, Grundy SM, Waters DD, et al; Treating to New Targets (TNT) Investigators. Intensive lipid lowering with atorvastatin in patients with stable coronary disease. N Engl J Med 2005; 352:1425–1435.
- Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002; 360:7–22.
- Baigent C, Blackwell L, Emberson J, et al; Cholesterol Treatment Trialists’ (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet 2010; 376:1670–1681.
- LIPID Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. The Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. N Engl J Med 1998; 339:1349–1357.
- Grundy SM, Cleeman JI, Bairey Merz CN, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 2004; 110:227–239.
- American Diabetes Association. Executive summary: standards of medical care in diabetes—2012. Diabetes Care 2012; 35(suppl 1):S5–S10.
- Daniels SR, Greer FR; Committee on Nutrition. Lipid screening and cardiovascular health in childhood. Pediatrics 2008; 122:198–208.
- Knowler WC, Barrett-Connor E, Fowler SE, et al; Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346:393–403.
- Cholesterol Treatment Trialists’ (CTT) Collaborators; Mihaylova B, Emberson J, Blackwell L, et al. The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. Lancet 2012; 380:581–590.
- US Food and Drug Administration. Statin drugs—drug safety communication: class labeling change. February 28, 2012. http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm293670.htm.
- Freeman DJ, Norrie J, Sattar N, et al. Pravastatin and the development of diabetes mellitus: evidence for a protective treatment effect in the West of Scotland Coronary Prevention Study. Circulation 2001; 103:357–362.
- Sever PS, Dahlof B, Poulter NR, et al; ASCOT investigators. Prevention of coronary and stroke events with atorvastatin in hypertensive patients who have average or lower-than-average cholesterol concentrations, in the Anglo-Scandinavian Cardiac Outcomes Trial–Lipid Lowering Arm (ASCOT-LLA): a multicentre randomised controlled trial. Lancet 2003; 361:1149–1158.
- Colhoun HM, Betteridge DJ, Durrington PN, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004; 364:685–696.
- Collins R, Armitage J, Parish S, Sleigh P, Peto R; for the Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol-lowering with simvastatin in 5963 people with diabetes: a randomised placebo-controlled trial. Lancet 2003; 361:2005–2016.
- Ridker PM, Danielson E, Fonseca FA, et al. Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein. N Engl J Med 2008; 359:2195–2207.
- Shepherd J, Blauw GJ, Murphy MB, et al; PROSPER Study Group. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002; 360:1623–1630.
- Rajpathak SN, Kumbhani DJ, Crandall J, Barzilai N, Alderman M, Ridker PM. Statin therapy and risk of developing type 2 diabetes: a meta-analysis. Diabetes Care 2009; 32:1924–1929.
- Keech A, Colquhoun D, Best J, et al. Secondary prevention of cardiovascular events with long-term pravastatin in patients with diabetes or impaired fasting glucose—results from the LIPID trial. Diabetes Care 2003; 26:2713–2721.
- Kjekshus J, Apetrei E, Barrios V, et al. Rosuvastatin in older patients with systolic heart failure. N Engl J Med 2007; 357:2248–2261.
- Sattar N, Preiss D, Murray HM, et al. Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials. Lancet 2010; 375:735–742.
- Nakamura H, Arakawa K, Itakura H, et al. Primary prevention of cardiovascular disease with pravastatin in Japan (MEGA Study): a prospective randomised controlled trial. Lancet 2006; 368:1155–1163.
- Downs JR, Clearfield M, Weis S, et al. Primary prevention of acute coronary events with lovastatin in men and women with average cholesterol levels: results of AFCAPS/TexCAPS. Air Force/Texas Coronary Atherosclerosis Prevention Study. JAMA 1998; 279:1615–1622.
- Scandinavian Simvastatin Survival Study study group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S). Lancet 1994; 344:1383–1389.
- Barzilay JI, Davis BR, Pressel SL, et al; ALLHAT Collaborative Research Group. Long-term effects of incident diabetes mellitus on cardiovascular outcomes in people treated for hypertension: the ALLHAT Diabetes Extension Study. Circ Cardiovasc Qual Outcomes 2012; 5:153–162.
- Tavazzi L, Maggioni AP, Marchioli R, et al. Effect of rosuvastatin in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial. Lancet 2008; 372:1231–1239.
- GISSI Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico). Results of the low-dose (20 mg) pravastatin GISSI Prevenzione trial in 4271 patients with recent myocardial infarction: do stopped trials contribute to overall knowledge? Ital Heart J 2000; 1:810–820.
- Yamakawa T, Takano T, Tanaka S, Kadonosono K, Terauchi Y. Influence of pitavastatin on glucose tolerance in patients with type 2 diabetes mellitus. J Atheroscler Thromb 2008; 15:269–275.
- Kryzhanovski V, Gumprecht J, Zhu B, Yu CY, Hounslow N, Sponseller CA. Atorvastatin but not pitavastatin significantly increases fasting plasma glucose in patients with type 2 diabetes and combined dyslipidemia (abstract). J Am Coll Cardiol 2011; 57:E575.
- Simsek S, Schalkwijk CG, Wolffenbuttel BH. Effects of rosuvastatin and atorvastatin on glycaemic control in type 2 diabetes—the CORALL study. Diabet Med 2012; 29:628–631.
- Sabatine MS, Morrow DA, Giugliano RP, et al. Implications of upstream glycoprotein IIb/IIIa inhibition and coronary artery stenting in the invasive management of unstable angina/non-ST-elevation myocardial infarction: a comparison of the Thrombolysis In Myocardial Infarction (TIMI) IIIB trial and the Treat angina with Aggrastat and determine Cost of Therapy with Invasive or Conservative Strategy (TACTICS)-TIMI 18 trial. Circulation 2004; 110(suppl III):834–880.
- Shepherd J, Barter P, Carmena R, et al. Effect of lowering LDL cholesterol substantially below currently recommended levels in patients with coronary heart disease and diabetes: the Treating to New Targets (TNT) study. Diabetes Care 2006; 29:1220–1226.
- Waters DD, Ho JE, DeMicco DA, et al. Predictors of new-onset diabetes in patients treated with atorvastatin: results from 3 large randomized clinical trials. J Am Coll Cardiol 2011; 57:1535–1545.
- Yousef A, Tu JV, Wang J, Donovan L, Ko DT. The association of intensive statin therapy on long-term risks of cardiovascular events and diabetes following acute myocardial infarction (abstract). Circulation 2012; 125:e859.
- Preiss D, Seshasai SR, Welsh P, et al. Risk of incident diabetes with intensive-dose compared with moderate-dose statin therapy: a metaanalysis. JAMA 2011; 305:2556–2564.
- de Lemos JA, Blazing MA, Wiviott SD, et al; A to Z Investigators. Early intensive vs a delayed conservative simvastatin strategy in patients with acute coronary syndromes: phase Z of the A to Z trial. JAMA 2004; 292:1307–1316.
- Pedersen TR, Faegeman O, Kastelein JJ, et al; Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL) Study Group. High-dose atorvastatin vs usual-dose simvastatin for secondary prevention after myocardial infarction: the IDEAL study: a randomized controlled trial. JAMA 2005; 294:2437–2445.
- Armitage J, Bowman L, Wallendszus K, et al; Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH) Collaborative Group. Intensive lowering of LDL cholesterol with 80 mg versus 20 mg simvastatin daily in 12,064 survivors of myocardial infarction: a double-blind randomised trial. Lancet 2010; 37:1658–1669.
- Ridker PM, Pradhan A, MacFadyen JG, Libby P, Glynn RJ. Cardiovascular benefits and diabetes risks of statin therapy in primary prevention: an analysis from the JUPITER trial. Lancet 2012; 380:565–571.
- Brunzell JD, Davidson M, Furberg CD, et al; American Diabetes Association; American College of Cardiology Foundation. Lipoprotein management in patients with cardiometabolic risk: consensus statement from the American Diabetes Association and the American College of Cardiology Foundation. Diabetes Care 2008; 31:811–822.
- Koh KK, Quon MJ, Han SH, Lee Y, Kim SJ, Shin EK. Atorvastatin causes insulin resistance and increases ambient glycemia in hypercholesterolemic patients. J Am Coll Cardiol 2010; 55:1209–1216.
- Koh KK, Quon MJ, Han SH, et al. Differential metabolic effects of pravastatin and simvastatin in hypercholesterolemic patients. Atherosclerosis 2009; 204:483–490.
- Nakata M, Nagasaka S, Kusaka I, Matsuoka H, Ishibashi S, Yada T. Effects of statins on the adipocyte maturation and expression of glucose transporter 4 (SLC2A4): implications in glycaemic control. Diabetologia 2006; 49:1881–1892.
- Yada T, Nakata M, Shiraishi T, Kakei M. Inhibition by simvastatin, but not pravastatin, of glucose-induced cytosolic Ca2+ signalling and insulin secretion due to blockade of L-type Ca2+ channels in rat islet beta-cells. Br J Pharmacol 1999; 126:1205–1213.
- Guyton JR, Fazio S, Adewale AJ, et al. Effect of extended-release niacin on new-onset diabetes among hyperlipidemic patients treated with ezetimibe/simvastatin in a randomized controlled trial. Diabetes Care 2012; 35:857–860.
- Canner PL, Furberg CD, Terrin ML, McGovern ME. Benefits of niacin by glycemic status in patients with healed myocardial infarction (from the Coronary Drug Project). Am J Cardiol 2005; 95:254–257.
- Grundy SM, Vega GL, McGovern ME, et al; Diabetes Multicenter Research Group. Efficacy, safety, and tolerability of once-daily niacin for the treatment of dyslipidemia associated with type 2 diabetes: results of the Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial. Arch Intern Med 2002; 162:1568–1576.
- Gupta AK, Dahlof B, Dobson J, Sever PS, Wedel H, Poulter NRAnglo-Scandinavian Cardiac Outcomes Trial Investigators. Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial—Blood Pressure Lowering Arm and the relative influence of antihypertensive medication. Diabetes Care 2008; 31:982–988.
- Elliott WJ, Meyer PM. Incident diabetes in clinical trials of antihypertensive drugs: a network meta-analysis. Lancet 2007; 369:201–207.
- Jong JP, Chang MH, Tien L, et al. Antihypertensive drugs and new-onset diabetes: a retrospective longitudinal cohort study. Cardiovasc Ther 2009; 27:159–163.
- Third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation 2002; 106:3143–3421.
- Norhammar A, Tenerz A, Nilsson G, et al. Glucose metabolism in patients with acute myocardial infarction and no previous diagnosis of diabetes mellitus: a prospective study Lancet 2002; 359:2140–2144.
- Haffner SM, Lehto S, Ronnemaa T, Pyorala K, Laakso M. Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction. N Engl J Med 1998; 339:229–234.
- Sprafka JM, Burke GL, Folsom AR, McGovbern PG, Hahn LP. Trends in prevalence of diabetes mellitus in patients with myocardial infarction and effect of diabetes on survival. The Minnesota Heart Survey. Diabetes Care 1991; 14:537–543.
- Geiss LS, Herman WH, Smith PJ. Mortality in non-insulin-dependent diabetes. In:Harris MI, Cowie CC, Stern MP, et al, editors. Diabetes in America. 2nd ed. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, 1995:233–257.
- Stamler J, Vaccaro O, Neaton JD, Wentworth D. Diabetes, other risk factors, and 12-yr cardiovascular mortality for men screened in the Multiple Risk Factor Intervention Trial. Diabetes Care 1993; 16:434–444.
- Turner RC, Millns H, Neil HA, et al. Risk factors for coronary artery disease in non-insulin dependent diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS: 23). BMJ 1998; 316:823–828.
- Gaede P, Vedel P, Larsen N, Jensen GV, Parving HH, Pedersen O. Multifactorial intervention and cardiovascular disease in patients with type 2 diabetes. N Engl J Med 2003; 348:383–393.
- Gaede P, Pederson O. Intensive integrated therapy of type 2 diabetes: implications for long-term prognosis. Diabetes 2004; 53:S39–S47.
- Goldberg RB, Mellies MJ, Sacks FM, et al. Cardiovascular events and their reduction with pravastatin in diabetic and glucose-intolerant myocardial infarction survivors with average cholesterol levels: subgroup analyses in the cholesterol and recurrent events (CARE) trial. The Care Investigators. Circulation 1998; 98:2513–2519.
- Pyðrälä K, Pedersen TR, Kjekshus J, Faergeman O, Olsson AG, Thorgeirsson G. Cholesterol lowering with simvastatin improves prognosis of diabetic patients with coronary heart disease. A subgroup analysis of the Scandinavian Simvastatin Survival Study (4S). Diabetes Care 1997; 20:614–620.
- Vijan S, Hayward RA; American College of Physicians. Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians. Ann Intern Med 2004; 140:650–658.
- Baigent C, Keech A, Kearney PM, et al; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005; 366:1267–1278. Errata in Lancet 2008; 371:2084, Lancet 2005; 366:1358.
- Brugts JJ, Yetgin T, Hoeks SE, et al. The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials. BMJ 2009; 338:b2376.
- Kearney PM, Blackwell L, Collins R, Keech A, Simes J, Baigent C; Cholesterol Treatment Trialists’ (CTT) Collaborators. Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis. Lancet 2008; 371:117–125.
- Nissen SE, Nicholls SJ, Sipahi I, et al; ASTEROID Investigators. Effect of very high-intensity statin therapy on regression of coronary atherosclerosis: the ASTEROID trial. JAMA 2006; 295:1556–1565.
- Cannon CP, Braunwald E, McCabe CH, et al; Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis in Myocardial Infarction 22 Investigators. Intensive versus moderate lipid lowering with statins after acute coronary syndromes et al. N Engl J Med 2004; 350:1495–1504.
- LaRosa JC, Grundy SM, Waters DD, et al; Treating to New Targets (TNT) Investigators. Intensive lipid lowering with atorvastatin in patients with stable coronary disease. N Engl J Med 2005; 352:1425–1435.
- Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002; 360:7–22.
- Baigent C, Blackwell L, Emberson J, et al; Cholesterol Treatment Trialists’ (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet 2010; 376:1670–1681.
- LIPID Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. The Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. N Engl J Med 1998; 339:1349–1357.
- Grundy SM, Cleeman JI, Bairey Merz CN, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 2004; 110:227–239.
- American Diabetes Association. Executive summary: standards of medical care in diabetes—2012. Diabetes Care 2012; 35(suppl 1):S5–S10.
- Daniels SR, Greer FR; Committee on Nutrition. Lipid screening and cardiovascular health in childhood. Pediatrics 2008; 122:198–208.
- Knowler WC, Barrett-Connor E, Fowler SE, et al; Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002; 346:393–403.
- Cholesterol Treatment Trialists’ (CTT) Collaborators; Mihaylova B, Emberson J, Blackwell L, et al. The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. Lancet 2012; 380:581–590.
KEY POINTS
- The evidence from individual clinical trials is mixed, but meta-analyses indicate that statin therapy is associated with approximately a 9% higher risk of diabetes (an absolute difference of about 0.4%).
- We need to interpret this information cautiously. Many potentially confounding factors are involved, and rigorous prospective trials are needed to examine this issue.
- The benefit of preventing serious cardiovascular events seems to outweigh the higher risks of diabetes and poorer glycemic control, and we should continue to give statins to patients at moderate to high risk, including those with diabetes, with vigilance for these side effects.