Prevention of type 2 diabetes: role of metformin.

Metformin lowers moderate (nondiabetic) fasting hyperglycaemia in individuals at risk for type 2 diabetes without causing hypoglycaemia. In addition, it has demonstrated favourable action on several cardiovascular risk factors that are often present in these individuals: it favours the maintenance of diet-induced weight loss and its associated improvement in fibrinolysis; and it lowers plasma concentrations of fasting insulin, total and low density lipoprotein-cholesterol, free fatty acids, and of two markers of endothelial damage--tissue plasminogen activator antigen and von Willebrand factor. These effects together with the good tolerability profile of the drug position metformin as a first-line agent for the prevention of type 2 diabetes.