Results:

Three randomized clinical trials (RCTs) (N = 290; including one trial of 150 patients with type 2 diabetes and mean BMI of 37, one trial of 80 patients without diabetes [38% with metabolic syndrome] and BMI of 30-35, and one trial of 60 patients with diabetes and BMI of 30-40 [13 patients with BMI <35]) found that surgery was associated with greater weight loss (range, 14.4-24 kg) and glycemic control (range, 0.9-1.43 point improvements in glycated hemoglobin levels) during 1-2 years of follow-up than nonsurgical treatment. Indirect comparisons of evidence from observational studies of bariatric procedures (600 patients) and meta-analyses of nonsurgical therapies (containing more than 300 RCTs) support this finding at 1 or 2 years of follow-up. However, there are no robust surgical data beyond 5 years of follow-up on outcomes of diabetes, glucose control, or macrovascular and microvascular outcomes. In contrast, some RCT data of nonsurgical therapies show benefits at 10 years of follow-up or more. Surgeon-reported adverse events were low (e.g., hospital deaths of 0.3%-1.0%), but data were from select centers and surgeons. Long-term adverse events are unknown.