Do Statins Really Increase Risk Of Diabetes?

A headline in the New York Times on Wednesday, June 22, 2011 caught my eye:  “Study finds higher risk of diabetes from statins.”  The report, written by Tara Parker-Pope,  summarized the results of a study published the day before in the The Journal of the American Medical Association (JAMA).  The investigators (Dr. Kausik Ray and colleagues) carried out some old-fashioned data-mining, analyzing results of 5 previously published studies,  and found that statins (e.g., Lipitor), a class of drugs used to treat high cholesterol levels, were associated with a slightly increased risk (12%) of developing diabetes mellitus.  For patients who took high doses of statins, the risk was about 20%.

Is this new and exciting information?

The association between statin use and slightly increased risk of diabetes is not a new observation; last year The Lancet published a study of 90,000 patients taking statins and showed an increased risk of about 9% (the present study included about 32,000 patients).  So, these new data are mostly “same old same old.”  In fact, I am not sure why the study got so much attention by the New York Times, other than many people take statins and article was published in JAMA.  Anyway, the article quoted Dr. Steven Nissen, a cardiologist from the Cleveland Clinic, who said he didn’t think the information was very important. What I found amazing was that neither the author of the newspaper article or any of the people quoted in the article raised the possibility that the study findings really had nothing at all to do with statins causing diabetes.  For example, maybe the association is related to the fact that more people who develop diabetes have lipid abnormalities and are more likely to be treated with statins?  Instead, the article focused on the possible mechanisms by which statins could lead to the development of diabetes.   The only way to answer this question would be to do a long-term randomized clinical trial in which patients with abnormal lipid levels were either treated with statins or just monitored.  I am not suggesting that such a study be carried out since it probably wouldn’t be ethical given the proven  benefits of statins to treat lipid abnormalities and decrease risk for the development of cardiovascular disease.  What I am suggesting is that those who write articles in newspapers and magazines about medical studies, be more careful to make sure readers understand the difference between cause/effect and association.  This was not even considered in this New York Times article.

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