Roux-en-Y-Gastric Bypass vs. Lifestyle Modification and Medical Therapy in the Treatment of Type 2 Diabetes

Inclusion Criteria: 1. Diagnosed with type 2 diabetes by any of the following: * A fasting plasma glucose \> 126 mg/dl confirmed on repeated testing * 2 hour plasma glucose \> 200mg/dl during a 75 gram oral glucose tolerance test * HbA1c \>6.5% 2. A normal or high C-peptide level (\> 0.9 ng/ml) to exclude type 1 diabetes and insulin deficient type 2 diabetes 3. Negative AntiGAD 65 Antibodies 4. Body mass index (BMI) between 28 and 35 kg/m2 ( \> 27.6 kg/m2 and \< 34.5 kg/m2 ) that reflect a condition of overweight to moderate obesity. In consideration of the evidence that the associations between BMI, percentage of body fat, and CV risk differ across populations, and that the proportion of Asian people with a high risk of type 2 diabetes and cardiovascular disease is substantial at BMI's lower than the existing WHO cut-off point for overweight (= 25 kg/m2) (source: WHO Expert consultation. Lancet. 2004 Jan 10;363(9403):157-63), the lower BMI cut-off for inclusion in this study will be 26kg/m2 for patients of Asian descent. 5. No contraindications for surgery or General Anesthesia as determined by a multidisciplinary team (surgeon, endocrinologist/internist, cardiologist, nutritionist) 6. . Between 21 and 65 years of age 7. . Able to provide informed consent 8. . If a female with reproductive potential, agreement to use a reliable method of birth control for 2 years following surgery (Barrier, birth control, patch). This precaution is necessary to prevent potential complications of pregnancy due to possible nutritional deficiencies in the period of more intense weight loss after surgery. On the other hand, this precaution will avoid erratic weight/glucose tolerance changes of pregnancy effecting results. 9. Have valid health insurance Exclusion Criteria: 1. Diagnosis of diabetes more than 15 years (to exclude pts with significant decline in pancreatic function from long-standing diabetes) 2. Insulin therapy for more than 12 years 3. HbA1c higher than 10% 4. Diagnosis of type 1 diabetes 5. Enrolled in another clinical study which involves an investigational drug 6. Major psychological disorders 7. Pregnancy (all female patients will have serum beta hCG) or planned pregnancy within two years of entry into the study or unwilling to use reliable contraceptive method 8. Previous gastric or esophageal surgery 9. Immunosuppressive drugs including corticosteroids 10. Coagulopathy (INR \> 1.5 or platelets \< 50,000/μl) 11. Anemia (Hb \< 10.0 g/dl) 12. Any contraindication to laparoscopic gastric bypass or medical diabetes therapy 13. A severe concurrent illness likely to limit life (e.g. cancer) or requiring extensive systemic treatment (e.g. ulcerative colitis) 14. A significant malabsorptive or gastrointestinal disorder (e.g. pancreatic insufficiency, Celiac sprue, or Crohn's disease) 15. Significant proteinuria (\> 250 mg/dl) 16. Severe neuropathy or clinical diagnosis of gastropathy (early satiety, nausea, vomiting, constipation alternating with diarrhea) 17. Myocardial infarction in the previous year, current angina or heart failure