Do Statins Cause Diabetes?

Statins are a class of drugs commonly used to lower LDL cholesterol, which is thought to contribute to adverse cardiovascular events when levels are elevated. Several clinical trials have suggested that a side effect of statin use is the development of diabetes. Conversely, numerous clinical trials involving statins have demonstrated they are protective against diabetes contraction. A new study published in the journal The Lancet performed a meta-analysis of published and unpublished data from statin clinical trials to assess whether this drug class does indeed increase the risk of diabetes (1).

The study assessed data from 13 large randomized clinical trials that monitored blood glucose levels, followed up with patients longer than a year, were placebo controlled, and did not include diabetic patients at baseline. The 13 trials included a total of 91,140 patients that were used in the meta-analysis.

Of the 91,140 patients in the trials, 4,278 developed diabetes. 2,226 that acquired diabetes were treated with statins and 2,052 were control patients. The authors calculated that the odds ratio for the development of diabetes with statin treatment was a statistically significant 9% during the follow up period for the pooled data. The authors also calculated that for every 255 patients treated for 4 years with a statin, 1 patient will develop diabetes. Age appeared to be a contributing factor, as the odds ratio for the development of diabetes was higher in older patients. Those 65 and above seem to be at the highest risk for diabetes under statin treatment.

The trial did not include those already afflicted with diabetes to address whether these patients were more likely to improve or worsen their glycemic control. It is unknown if, in the patients that develop diabetes, any benefit from a statin is negated by eventual diabetes related events in the long term. Statins may also be used in combination with other lipid lowering drugs, such as niacin, that have been demonstrated to worsen blood glucose control. It will be interesting to see if such combinations actually increase the risk of diabetes further and if long term benefits outweigh the risks in certain population pools.

The authors suggest that current clinical practice with statins should not be changed, although monitoring for diabetes in older patients is suggested. Prescribers should use good clinical judgement with patients where statin benefit is unclear, or offers marginal benefit (2). Diabetes development carries its own plethora of adverse outcomes and its progression should not be assisted by unwarranted drug use. Responsible clinicians will weigh the risks and benefits for each individual patient with this data in mind.

References:

1. Sattar, N. et, al. 2010. The Lancet. 375: 735-42
2. Manuel, D. et, al. 2006. BMJ. 332 (7555): 1419