The study aims at describing the acute and subacute changes after Roux-en-Y (RYGB) gastric bypass in insulin secretion from the beta cell and glucagon secretion from the alpha cell as well as the stimulatory effect of the incretins on the pancreatic islets. RYGB is a bariatric procedure that changes the gastrointestinal anatomy and has been demonstrated to cause remission of type 2 diabetes shortly after the operation, before any significant weight loss. The altered transit of nutrient through the gastrointestinal tract after the operation is thought to play a key role in this remission and studies have shown significant changes in the secretion of gut hormones, namely the incretin hormone glucagon-like peptide-1 (GLP-1). However it is unknown whether the secretory function of the pancreatic islets as well as the stimulatory effect of the incretin hormones is changes postoperatively.

Inclusion Criteria:

• Normal glucose tolerance
• Age > 18 years
• BMI > 40 or > 35 if combined with hypertension or obstructive sleep apnoea
• Caucasian
• Normal hemoglobinaemia
• Signed informed consent

Exclusion Criteria:

• Major psychiatric disorder
• Alcohol or drug abuse
• Major hearth or pulmonary disease
• Previous major abdominal disease (e.g. peritonitis, large hernia)
• Pregnancy/lactation
• Treatment with GLP-1 analogs

Subjects are recruited from the population undergoing gastric bypass surgery at Hvidovre Hospital