Previous studies have shown, that laparoscopic Roux-en-Y gastric bypass (LRYGB), and also laparoscopic sleeve gastrectomy (LSG) leed to a significant improvement of glucose metabolism and in many cases to a complete remission of diabetes type II in obese patients. It is still unclear which mechanisms underlie these changes. Since the positive effects of bariatric surgery have been investigated within few days after surgical intervention, before significant weight loss has been achieved, the caloric restriction has been discussed as a possible mechanism.~The aim of the study is to investigate, if bariatric surgery or the related caloric restriction causes the significant improvement of glucose metabolism, which has been found in bariatric patients. Therefore, the investigator will examine obese patients with diabetes type II or impaired glucose metabolism regarding possible metabolic changes within few days after bariatric surgery (LSG or LRYGB) or caloric restriction only.~Group I: Patients undergoing LSG; Group II: Patients undergoing LRYGB; Group III (Control group): Patients undergoing caloric restriction;~Dietetic, anthropometric, metabolic and hormonal parameters will be measured. Primary outcome marker is the insulin sensitivity according to Matsuda (MISI).~The project is a prospective, controlled study. Study examinations will be performed before intervention, and one, two, three, four and five days after (start of) intervention, as well after one month.
The aim of the study is to investigate, if bariatric surgery or the related caloric restriction causes the significant improvement of glucose metabolism, which has been found in bariatric patients.