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Updated June 29, 2015.
Several studies have shown that patients treated with statin drugs have a higher risk of developing type 2 diabetes. While doctors were initially reluctant to accept the association between statins and diabetes, over the last few years the evidence has become quite solid. People who take statins are more likely to develop diabetes.
However, the common feeling among experts has been that, because statins are used in patients who have significant risk factors for heart disease, these are people who likely have a much higher baseline risk of developing diabetes.
So, the thinking has gone, perhaps the statins are just accelerating the inevitable a little bit.
But a study published in April, 2015 appears to throw some cold water on this soothing speculation.
Investigators writing in the Journal of General Internal Medicine looked at the records of healthy statin users in the Veterans Administration system, and compared them to similar patients not taking statins. By “healthy,” they meant patients who had no known cardiovascular disease or diabetes, or any other serious chronic diseases.
They found that, during follow-up, patients taking statins had an 85% increased risk of developing diabetes compared to non-statin users. They also had an increased risk of developing complications from their diabetes - and more of them became overweight or obese.
What This Means
This is a retrospective study, so it does not prove anything. However, it suggests two things that are new.
First, the risk of diabetes in statin users may not be limited to the sickest patients, that is, to patients who may already have a greatly increased risk of developing diabetes. Even the relatively healthy statin users appear to have this risk.
Second (and this may be the more surprising and disturbing finding), when diabetes occurs while taking statins, the risk of developing the complications of diabetes may be higher than among non-statin users. So, if statins do cause diabetes, it’s not some “milder” form of the disease (as has been speculated). It’s real, honest-to-goodness diabetes.
The Bottom Line
The experts on preventive cardiology are not going to change any of their recommendations based on one retrospective analysis, and we should not expect them to.
People who already have coronary artery disease (CAD), especially survivors of myocardial infarction or acute coronary syndrome, still have a strong reason to take statins. Despite the risk of diabetes (and the other risks associated with these drugs), their overall risk of experiencing further cardiovascular events or death is significantly reduced by statins.
It does make sense, however, to take this new information into account if you and your doctor are considering statins for primary prevention, that is, if you have risk factors for CAD, but no overt heart disease. These are the “healthy” patients analyzed in this new study, and whose risk of diabetes appeared to be increased by statins.
The experts, whose job it is to weigh all the evidence then make recommendations for the whole population, generally will not give much if any credence to unproven associations like this one. And, based on well-conducted clinical trials, the use of statins for primary prevention makes a lot of sense. But your job is to weigh the risk/benefit ratio for you yourself - so it’s perfectly acceptable for you to include risks that have not yet been proven in definitive clinical trials.
Sources:
Mansi I, Frei CR, Wang C, et al. Statins and New-Onset Diabetes Mellitus and Diabetic Complications: A Retrospective Cohort Study of US Healthy Adults. Journal of General Internal Medicine, April, 2015 abstract (Accessed 6/19/15)