Applicable and Beneficial Populations for Bariatric Surgery for Diabetes According to current analysis, the greatest effect of bariatric surgery is to cause weight loss in patients with diabetes. Therefore, it is still important to limit the surgery to obese patients. Previously, bariatric surgery was restricted to patients with extreme obesity, whereas it is now believed that bariatric surgery can be considered in moderately obese patients with poorly controlled diabetes. Therefore, obesity is still a necessary condition, but the criteria have just been relaxed. In general, weight can be classified as normal weight, overweight, obese, moderately obese, and extremely obese. Patients who are mildly obese or only overweight should not be considered for bariatric surgery. The beneficiary population of weight loss surgery is first of all patients whose blood glucose cannot be controlled by current medication on the basis of lifestyle interventions. Such patients are at high risk of developing a range of future diabetic complications. It is unrealistic to rely on surgery alone to get a clean break without medication and lifestyle interventions that follow the standards of diabetes treatment.