There is evidence that gastrointestinal operations for non weight-losing purposes are beneficial for diabetes mellitus. Aiming to analyze such hypothesis, patients submitted to gastric bypass for morbid obesity, gastrectomy for gastric cancer and colectomy for colo-rectal cancer will be compared. The end point will be changes in fasting blood glucose and hemoglobin A1c concentration.

In a prospective protocol with retrospective information, patients (N=240) undergoing bariatric Roux-en-Y gastric bypass (n=80), cancer subtotal or total gastrectomy (n=80) and right colectomy or rectosigmoidectomy (n=80) with follow-up >3 years free of disease, with or without previously impaired fasting blood glucose, will be recruited. Patients will be submitted to a questionnaire involving diet, diagnosis of diabetes and glucose-lowering drugs, body weight and other clinical items. Preoperative information available in the hospital system will be completed and current findings will be updated, including body mass index and biochemical measurements. Using the outcomes of the bariatric population as benchmark, both concerning diabetics that were ameliorated and nondiabetics that progressed to new-onset diabetes,results in the other groups will be compared. The study should answer whether gastric and colorectal surgery for cancer 1) Are beneficial for established diabetes; 2) Attenuate the conversion of normal patients to diabetes, both within a follow-up period of 3- 12 years;

Inclusion Criteria:

• Follow-up period > 3 years,
• weight stable in the last year

Exclusion Criteria:

• Reoperation or take-down of original operation,
• consumptive diseases,
• protein-calorie malnutrition,
• organ failures,
• pancreatic surgery,
• cell or organ transplantation,
• type 1 diabetes,
• cognitive impairment or Alzheimer disease,
• refusal to participate in the protocol

Adult males and females submitted to elective curative operations will be enrolled