The major environmental factors that increase the risk of type 2 diabetes, presumably in the setting of genetic risk, are overnutrition and a sedentary lifestyle, with consequent overweight and obesity. The high rate of weight regain has limited the role of lifestyle interventions as an effective means of controlling glycemia long term. The aims of the present study were: 1) To compare the effectiveness and safety of two nutritional protocols - namely low-carbohydrate Mediterranean diet or low-fat diet - in newly-diagnosed, drug-naive overweight patients with type 2 diabetes mellitus. The primary aim of the study was the effect on hemoglobin A1c levels; secondary aims were time to introduction of the first hypoglycemic agent, prevalence of the metabolic syndrome, percentage of patients meeting ADA goals for risk factors (HbA1c, blood pressure, LDL-cholesterol, percentage of patients with HbA1c < 7%.