The treatment of obesity is strongly recommended because it exacerbates insulin resistance, hypertension, dyslipidemia and atherosclerosis, and represents a risk factor for type 2 diabetes. Although diet and exercise are valuable in this treatment, patient compliance is a major problem. Sibutramine has been shown to be a highly effective pharmacotherapy for weigh loss in obese patients, mediated by increased satiety and an enhancement of energy expenditure. Metformin is widely used for glycemia control and is associated with a small to moderate body weight loss. We are assessing the combination of sibutramine and metformin, two agents with different mechanisms of action for control of body weight and metabolic dysregulation.