Statins and increases in diabetes

Here is subject number 2 from the post on Evidence in Medicine by Dean Rind. The subject is on evidence for increases in type 2 diabetes among those who take statins to reduce cholesterol.

from: Dean Rind’s Evidence in Medicine blog 

The new analysis found that patients treated with statins had about a 9% higher risk of diabetes than those treated with placebo or other agents. When I started reading the analysis, I had the questions in the list above already in mind and so was prepared to challenge the meta-analysis on several fronts. The authors of the analysis had appropriately anticipated my concerns and, to the extent the data allowed, answered them:

1) Was this really a chance finding driven by JUPITER? Before JUPITER found an increased risk of diabetes, there had been little discussion of statins and diabetes risk. JUPITER’s findings could have been due to chance, but the publicity around the result could have triggered the meta-analysis. JUPITER was large enough to sway the results in the meta-analysis and perhaps lead to a self-fulfilling conclusion based in random variation. The meta-analysis, though, did a secondary analysis that excluded JUPITER, and found that the results were essentially the same.

2) Were the varying results in the trials due to random variation or true differences? The meta-analysis found little need to invoke anything more than randomness (as measured by a statistic called the I2). What had seemed to be conflicting results was likely nearly entirely due to random variation around a likely single true effect of slightly increased risk of diabetes.

3) Are some statins protective while others cause diabetes? The finding of little heterogeneity suggests the answer is no, but ultimately this is a hard question to answer definitively because of the more limited data about each individual statin. The meta-analysis found that the confidence intervals of the effects for individual statins overlapped such that it seemed unlikely that there were important differences among the statins, but it’s hard to be certain. Additionally, lipophilic and hydrophilic statins showed the same effects on diabetes. And beyond that, the meta-analysis found that one of the main trials that had suggested a protective effect of pravastatin on diabetes had used an unusual definition of diabetes, and the effect was not seen when they substituted a standard definition.

While no new trials were published, as a result of this meta-analysis we have a much better feel for the effect of statins on diabetes than we had a few weeks ago. So, if after hours of trying to answer clinical questions by reading Cochrane you find yourself wondering whether meta-analyses are ever worth the effort that seems to go into them, remember this one and how much we learned about diabetes and statins from a new analysis of existing data. more at


  1. Thanks for creating this site. Keep up the good work.

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