The rosiglitazone (Avandia) story sounds deceptively similar to that of other drugs that have been withdrawn in recent years because of emerging safety concerns, notably rofecoxib (Vioxx). But several of the lessons are importantly different and raise fundamental questions about the criteria for licensing new drugs for diabetes and the way that clinicians use evidence about such drugs to incorporate them into clinical practice.

The additional 80% relative risk of myocardial infarction attributed to rosiglitazone at recent hearings of the US Food and Drug Administration1 2 is probably comparable to that of several non-steroidal anti-inflammatory drugs that are still on the market.3 The scandal of rosiglitazone lies in the fact that we were prescribing the drug to reduce the serious consequences of type 2 diabetes, the most important of which is myocardial infarction. Yet because no licensing body demanded evidence of effect on cardiovascular risk at the time of licensing, 10 years after the release of rosiglitazone we still cannot accurately quantify the harm to which we were exposing our patients. As clinicians we did not increase this risk knowingly, but ignorantly, because we were focused on the wrong end point: glycated haemoglobin (haemoglobin A_1c). We had lost sight of the main reason for treating this complex and progressive disease, which is not to reduce glycaemia but to prevent complications.