Thirty type 2 diabetic patients will be submitted to biliopancreatic diversion and 20 to gastric bypass. Subjects will be monitored during a 5 year period to assess the effects of the operations on diabetes control.

Inclusion Criteria:

• Type 2 diabetes mellitus
• Duration of diabetes ≥ 3 years
• Poor glycemic control (i.e., HbA1c ≥ 7.5%) in spite of hypoglycemic therapy in accordance with good clinical practice (GCP)

Exclusion Criteria:

• Specific contraindication to obesity surgery or biliopancreatic diversion or gastric bypass
• Pregnancy
• Medical conditions requiring acute hospitalisation
• Severe diabetes complications or associated medical conditions [such as blindness, end-stage renal failure (i.e. serum creatinine >2 mg/dl), liver cirrhosis, malignancy, chronic congestive heart failure (NYHA class III and IV)]
• Recent (within preceding 12 months) myocardial infarction, stroke or TIA
• Unstable angina pectoris
• Psychological conditions which may hamper patient's cooperation
• Geographic inaccessibility
• Any condition which, in the judgment of the Investigator, may make risky the participation in the study or bias the results