This study will investigate the effects of gastric bypass surgery on type II diabetes. The study will recruit patients with type II diabetes having Roux-en-Y gastric bypass, patients without type II diabetes having Roux-en-Y gastric bypass, and control subjects (patients having gastroscopy, but no surgery). Targeted enrollment is 30 patients per group. Samples of intestine are taken prior to surgery in gastroscopy, during surgery, and 6 months after surgery during gastroscopy. Meal test with incretin measurements, and feces and blood samplings are performed before and after surgery