The clinical evidence available showed that glitazones reduce glycosylated haemoglobin by approximately 1%, and are more effective at higher doses than at lower doses. Glitazone treatment is associated with weight gain. No published data were available on the long-term effects of glitazone use. No prospective randomised controlled trials (RCTs) were found comparing pioglitazone to rosiglitazone, but the available evidence indicated that the two treatments had similar effects.