Thiazolidinediones (TZD) have recently been introduced as an oral hypoglycaemic agent. A vast amount of data indicates that TZD also exhibit beneficial cardiovascular effects. This article reports on the results from the large PROactive study. After 3 years of pioglitazone treatment a reduction in the frequency of death, non-fatal myocardial infarction and cerebral infarction was demonstrated in type 2 diabetic subjects. However, there were side effects in terms of cardial insufficiency and edema. Though this study provides some clear cut answers, it also raises a lot of questions.