Metabolic surgery for type 2 diabetes: appraisal of clinical evidence and review of randomized controlled clinical trials comparing surgery with medical therapy.

Bariatric surgical procedures were originally developed to treat morbid obesity where their benefits certainly outweigh their potential side effects. Although they are very beneficial in improving metabolic control in type 2 diabetes, there are many medical treatments that are also effective. The role of bariatric surgery as primary therapy for type 2 diabetes depends on whether the benefit exceeds the surgical and nutritional complications, which are significant. The ultimate role for bariatric surgery in treating type 2 diabetes can only be determined by large, long-term randomized clinical trials which compare clinical outcomes of bariatric surgery with those of current intensive medical treatment. The four reported small, mostly 1-year trials have shown superior glycemic control by surgery as compared with medical treatment, but at the expense of significant surgical complications and unknown nutritional liability. They show that future trials will have to be much larger and last for at least 5-10 years.