This article reviews the evidence, from both observational epidemiology and randomised clinical trials, that lifestyle modification as well as anti-diabetic drugs can reduce or delay the development of diabetes in overweight and obese patients with IGT. Particular consideration is given to the recently published XENDOS study which showed that the combination of orlistat and lifestyle changes over four years is safe and well tolerated, results in a weight loss of about six kg and reduces the risk of developing diabetes by 45% in obese IGT patients. Thus, addition of orlistat to lifestyle intervention has a greater diabetes-preventing effect than lifestyle modification alone.