The above study plan will shed new light on the livers impact on diabetes, obesity and the significant effect of RYGB and gastric sleeve surgery on blood sugar control. The gastric sleeve surgery entails less risk for complications during and after surgery, should the procedure show comparable results with RYGB it can potentially benefit more patients planned for bariatric surgery. We also aim to validate an easy conductible and physiological method for obtaining reliable estimates of glucose kinetics. This can potentially lead to more specific diagnosis of for instance pancreatic islet cell function or hepatic insulin resistance, and thereby improve medical treatment of type 2 diabetes. The study also aims to identify biomarkers that can help to predict, which patients will benefit the most RYGB and gastric sleeve surgery.