A recent study has put the safety of rosiglitazone, a widely used therapy for type 2 diabetes, under the spotlight. The study claims the treatment significantly increases the risk of myocardial infarction and that there is a borderline significant increased risk of death from cardiovascular causes. However, the makers of rosiglitazone — GlaxoSmithKline — refute these findings and say the study has significant limitations. Dawn Powell reviews the issues.