Differing effect of statins on insulin sensitivity in non-diabetics: A systematic review and meta-analysis

BackgroundTo determine whether individual statins had differing effects on insulin sensitivity (IS) in patients without pre-existing diabetes mellitus.MethodsA systematic literature search of MEDLINE, EMBASE and Cochrane CENTRAL was conducted through December 2008. Trials were included if they compared pravastatin, atorvastatin, rosuvastatin or simvastatin to placebo/control, excluded patients with diabetes, and reported data on insulin sensitivity/resistance. IS data was pooled and evaluated as standardized mean differences (SMDs) and 95% confidence interval (CI) using a random-effects model.Results16 studies (n = 1146) were included, with patients receiving pravastatin in three trials (n = 164), atorvastatin in five trials (n = 315), rosuvastatin in five trials (n = 419), and simvastatin in five trials (n = 369). When pooled as a class, statins had no significant impact on IS as compared with placebo/control [SMD −0.084 (95% CI −0.210 to 0.042); p = 0.19]. Pravastatin was found to significantly improved IS [SMD 0.342 (95% CI 0.032–0.621); p = 0.03], whereas simvastatin significantly worsened IS [SMD −0.321 (95% CI −0.526 to −0.117); p = 0.03].ConclusionsStatins do not appear to demonstrate a ‘class effect’ on IS in patients without diabetes. Differences between individual statins likely exist that may partially explain the findings of previously conducted meta-analyses examining the impact of statins on the development of diabetes.