The Effect of Roux-en-Y Gastric Bypass on Insulin Sensitivity in Type 2 Diabetes

Obesity has become a severe epidemic globally. With the rapid increase in obesity comes a pronounced rise in obesity-related disorders, especially type 2 diabetes. Weight loss achieved through lifestyle changes improves diabetes, but is very difficult to maintain over time. In contrast, Roux-en-Y gastric bypass (RYGB) surgery can induce long-term weight loss and remission of diabetes. Surprisingly, the resolution of type 2 diabetes occurs within days after surgery and before significant weight loss. The resolution of diabetes must therefore be explained by a response to the surgical alterations of the stomach and intestines: restriction in gastric volume and bypass of the stomach, duodenum and proximal jejunum. Severe insulin resistance in muscle and liver is the common defect in obesity and type 2 diabetes and may be improved or even reversed shortly after the operation. The aim of this study is to examine the acute changes in insulin sensitivity of muscle and liver by using hyperinsulinaemic euglycaemic clamp combined with glucose tracer to assess hepatic glucose production. Insulin signaling pathways will be studied in biopsies from muscle and subcutaneous fat as to explain the molecular basis of the changes in insulin sensitivity after RYGB. Insulin secretion will be evaluated in response to oral glucose as well as iv glucose-glucagon.