This study compared the effects of three diets - a low carbohydrate Mediterranean (LCM) diet, a traditional Mediterranean (TM) diet, and the 2003 American Diabetes Association (ADA) diet - on 259 overweight patients with type 2 diabetes over 12 months. The LCM diet resulted in greater reductions in HbA1c and triglyceride levels compared to the other diets. Only the LCM diet improved HDL cholesterol levels. All diets resulted in weight loss and improvements in cardiovascular risk factors, but the LCM diet was superior for improving glycemic control.