Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) induce substantial weight loss and improve glycemic control in patients with type 2 diabetes, but it is not clear whether these occur via the same mechanism. We compared absorption rates of glucose and protein, as well as profiles of gastro-entero-pancreatic hormones, in patients who had undergone SG or RYGB vs controls.