Experts say the evidence as a whole suggests that the risks are slight and that for most women who take statins, the benefits for preventing heart attack and stroke outweigh those risks.
Researchers analyzed data on nearly 154,000 women followed for an average of seven years.
Women who reported taking a statin such as Lipitor, Pravachol, Zocor, or other statin drugs were almost 50% more likely to report developing type 2 diabetes than women who did not take statins, according to principal researcher Yunsheng Ma, MD, PhD, MPH, of the University of Massachusetts Medical School.
Statin Users Report More Diabetes
The study included 153,840 postmenopausal women with an average age at enrollment of 63. Most were followed for about seven years.
None of the women had diabetes when they were included in the study, but 10,242 cases of self-reported diabetes were found by the end of follow-up.
Adults with diabetes are two to four times more likely to have heart disease or a stroke than adults without diabetes.
In fact, the American Diabetes Association recommends that in addition to lifestyle changes, all people with diabetes take a statin regardless of their cholesterol level or whether they have heart disease.
Study author Annie L. Culver tells WebMD that this recommendation should not change, but clinicians should also stress the importance of lifestyle in lowering heart attack and stroke risk.
"There is a tendency to believe that drugs are the answer, when it is clear that eating well, exercising, and making other lifestyle changes are hugely important for lowering diabetes and cardiovascular risk," Culver says.
New York University cardiologist Nieca Goldberg, MD, who specializes in treating women with heart disease, agrees that lifestyle is often overlooked when patients are placed on statins.
"Sometimes when people are on statins they think it is a license to eat anything they want," she says. "This is certainly not the case, especially after menopause when women seem to have a harder time metabolizing sugar. That's why I tell my patients to watch out for starches and sugar."
Statin, Diabetes Risk Seen in Earlier Studies
It is not clear if statin use caused the increased risk or if the women who took statins shared some other unidentified risk for diabetes.
But the study is not the first to suggest that statins may raise the risk for diabetes.
An analysis of 13 studies, published in February of 2010, found that statin users had a 9% increased risk for diabetes. Another study, published last June, suggested a similar increase in risk among patients taking high doses of statins.
If the drugs do increase diabetes risk, the studies suggest that the risk is an effect shared by all statins, Ma says.
Harvard Medical School and Brigham and Women's Hospital cardiologist Christopher P. Cannon, MD, remains convinced that for most people who take statins to lower their risk for heart attack and stroke, the benefits far outweigh the risks.
"These studies are a reminder that no drug is without side effects, but if there is a risk it is more than likely a very small one," he says.
A spokesman for Lipitor manufacturer Pfizer Inc. says the drug has been shown in multiple studies to reduce heart attack and stroke risk in high-risk patients, including those with type 2 diabetes.
"We believe the risk of diabetes is outweighed by the [healthy heart] benefits of Lipitor therapy and we encourage patients to work with their physicians to discuss their treatment options," Pfizer media representative MacKay Jimeson tells WebMD.