High doses of cholesterol-lowering drugs called statins may protect patients from heart attack, but a new analysis of five previous clinical trials finds that they may also increase patients’ risk of developing Type 2 diabetes.
The new study, which appeared Tuesday in the Journal of American Medical Association, included published and unpublished data on 32,752 patients. The analysis compared diabetes risk in those who took a high dose of a statin to control cholesterol — 80 mg daily of drugs like Zocor (simvastatin), Lipitor (atorvastatin) and Pravachol (pravastatin) — and those who took a lower dose of these medications.
Over a five-year period, a total of 2,749 patients in both groups developed Type 2 diabetes; those in the high-dose group had a 12% increased risk over the others.
The association between statins and Type 2 diabetes is not a surprise: a 2010 study in the journal Lancet suggested that people taking statins were 9% more likely to develop the disease than those who didn’t take the drugs.
Still, experts say the findings shouldn’t put people who need statins off the medication. The new study suggests that the cholesterol-lowering benefits of statins outweigh the small diabetes risk. According to the data, 498 people would have to take high-dose statins for a year before causing one new case of diabetes. In contrast, only 155 people would need to take high-dose statin therapy for year to prevent a heart attack.
Doctors aren’t sure why the medication is associated with higher rates of Type 2 diabetes, but one possible explanation is that they increase blood sugar levels. The New York Times’ Well blog reported:
[A]nimal studies suggest that statins can increase muscle resistance to insulin, resulting in higher levels of circulating blood sugar. [Study author Dr. Kausik Ray, professor of cardiovascular disease prevention at St. George's University of London,] notes that the patients in the studies were diagnosed with diabetes because of elevated blood sugar levels, but that the long-term consequences of higher blood sugar levels triggered by statin use aren’t known.
The findings may call into question the overall value of prescribing statins to healthy people to try to prevent heart disease. But for heart disease patients and those at risk, staying on the drugs is a good idea. NPR’s Shots blog reported:
Bottom line: the benefits of statin therapy for patients at risk for heart disease and strokes outweigh the risks. “Statins are the best therapy we have for cardiovascular disease,” Harvard cardiologist Christopher P. Cannon told Shots. … Cannon said it’s unlikely that doctors will change the way they treat their patients as a result of the finding.
Doctors should monitor patients taking high-dose statins carefully to track the development of Type 2 diabetes. And in addition to using statins, heart patients should also talk to their doctors about improving their diet, exercise and other lifestyle habits.