At a preceding screening day, an oral glucose tolerance test (OGTT) and a dual energy x-ray absorptiometry (DXA) scan will be performed to determine glucose tolerance and the distribution of muscle and adipose tissue. The study will be carried out on three separate days differing with respect to the hormones infused: GLP-1, GIP or placebo (saline) which are double blinded. The patients will meet from an overnight fast and an infusion of one of the hormones is initiated. At the same time labeled glucose will be infused to determine the endogenous hepatic glucose production. A glucose infusion is adjusted according to frequent plasma glucose measurements to maintain fasting glucose level. After 2 hours a steady state of the tracer is achieved and a 2 hour hyperglycemic clamp, 3 mmol/l above fasting glucose concentration will be started. The tracer infusions are continued during the hyperglycemia. After the 4 hour clamp an arginine bolus will be administered to measure the ability to increase the secretion of insulin and glucagon.