Bariatric surgery: effects on glucose homeostasis

PURPOSE OF REVIEW: This article provides an overview of the effect of bariatric surgery on type 2 diabetes. It focuses on current hypotheses about the mechanism of diabetes control after Roux-en-Y gastric bypass surgery, and discusses the relationship between gastrointestinal anatomy and glucose homeostasis. RECENT FINDINGS: Along with sustained body weight loss, all bariatric operations lead to improvement or resolution of comorbid disease states, particularly type 2 diabetes. Roux-en-Y gastric bypass and biliopancreatic diversion are the most effective methods to control diabetes, resulting in persistent normal concentrations of plasma glucose, insulin, and glycosylated haemoglobin in 80-100% of cases. Resolution of diabetes after such treatment typically occurs too fast to be accounted for by weight loss alone. Recent animal investigations using duodenal-jejunal bypass, a stomach-preserving experimental model of Roux-en-Y gastric bypass, have shown that diabetes control is not a mere collateral effect of the treatment of obesity, but directly results from the exclusion of the duodenum and proximal jejunum from the flow of nutrients. SUMMARY: Results from clinical series and animal studies suggest that type 2 diabetes is a potentially operable disease. This indicates the need for carefully conducted clinical trials to define the ideal candidate patients and the most suitable type of operation for surgical treatment of type 2 diabetes. Understanding the exact mechanism by which Roux-en-Y gastric bypass controls diabetes is a priority because such knowledge may help us to understand the relationship between gastrointestinal physiology and insulin resistance as well as to help us identify new targets for novel antidiabetic medications.