http://archinte.ama-assn.org/cgi/content/abstract/archinternmed.2011.625v2

"Statin use at baseline was associated with an increased risk of DM (hazard ratio [ HR ], 1.71; 95% CI, 1.61-1.83). This association remained after adjusting for other potential confounders (multivariate-adjusted HR, 1.48; 95% CI, 1.38-1.59) and was observed for all types of statin medications."

Not an intervention study, but still suggestive.