Early Changes of Diabetes Parameters After Obesity Therapy (ECODO)

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.

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 surgical procedure and aftercare is indicated and performed according to the routine clinical setting of the Hospital. Patients stay 5 days stationary after surgical treatment. They receive a defined easy digestible diet, starting with liquid and mash food.

The surgical procedure and aftercare is indicated and performed according to the routine clinical setting of the Hospital. Patients stay 5 days stationary after surgical treatment. They receive a defined easy digestible diet, starting with liquid and mash food.

Patients of the control group do not undergo surgical treatment. They undergo a caloric restriction diet for 5 days. This diet is adapted to the postoperative diet of the patients included in the two other groups.

Blood insulin is measured during a Mixed Meal Tolerance Test (MMTT). It is used to calculate the Homeostasis Model Assessment (HOMA) and Matsuda Insulin Sensitivity Index

Blood glucose is measured during a Mixed Meal Tolerance Test (MMTT). It is used to calculate the Homeostasis Model Assessment (HOMA) and Matsuda Insulin Sensitivity Index

Inclusion Criteria: BMI (Body Mass Index) ≥ 35 kg/m2 Clinical diagnosis of type II diabetes or impaired glucose metabolism (Prediabetes: HbA1c > 5,7%, fasting glucose in capillary blood > 110 mg/dl - diagnosed by blood glucose test at the first study examination) Regarding the patients of the surgical groups: Indication to surgical therapy of obesity (laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass). The indication to surgery is independent of the study. The surgeon decides about that in the clinical routine according to the German S3 guideline. Written consent to participate int he study Exclusion Criteria: Medication use which affects glucose metabolism, except for diabetes medication (for example: glucocorticoids) Insulin need >1,0 IU/kg/d Experimental diabetes medication within the last three months Pregnancy Gastrointestinal diseases Uncontrolled hypo- or hyperthyroidism Status after bariatric or other gastrointestinal surgery