These trials support the contention that thiazolidinediones have superior efficacy in improving and stabilizing glycemic control than older antihyperglycemic agents, especially early in the course of type 2 diabetes. Findings from the Carotid Intima–media Thickness in Atherosclerosis using Pioglitazone add to the evidence that these agents have clinically meaningful vasculoprotective effects. Although generally well tolerated, they promote weight gain, limiting their acceptability to some extent, and occasionally lead to a diagnosis of heart failure, mostly in susceptible individuals.