Bariatric surgery: effects on glucose homeostasis

Abstract

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. 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. 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.