To assess the impact of weight loss due to bariatric surgery, as compared to the effect of optimal medical therapy alone on endothelial function, subclinical atherosclerosis, cardiovascular autonomic function in obese patient affected by type 2 diabetes.The study consists in a 2-arm randomized trial, in which patients will be randomly assigned to bariatric surgery or optimal medical therapy. Each patient will be studied at baseline (T0) and 12 months thereafter (T1).

Inclusion Criteria:

• type 2 diabetes: the American Diabetes Association (ADA) recommends the following criteria for diagnosis of diabetes: HbA1c ≥6.5% OR fasting plasma glucose‡ ≥126 mg/dL (7.0 mmol/L) OR 2-hour plasma glucose ≥200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test; 75-g glucose load should be used OR random plasma glucose concentration ≥200 mg/dL (11.1 mmol/L) in persons with symptoms of hyperglycemia or hyperglycemic crisis;
• indication to bariatric surgery: BMI ≥35 kg/m2 and one or more obesity related co-morbidities, including Type 2 Diabetes Mellitus.

Exclusion Criteria:

• overt cardiovascular disease (as assessed by clinical evaluation, physical examination, 12-lead ECG, 2D-echocardiogram);
• smoking habit;
• associated medical conditions, as chronic kidney disease (defined as creatinine clearance <60 mL/min/L.73m2), liver cirrhosis, malignancies, chronic congestive heart failure, acute or chronic inflammatory disease;
• specific contraindication to bariatric surgery;
• pregnancy;
• medical conditions requiring acute hospitalization;
• psychological conditions which may hamper patient's cooperation;
• geographic inaccessibility.