Roux-en-Y gastric bypass surgery (RYGB) improves glucose tolerance in patients with type 2 diabetes, but also changes the glucose profile in response to a meal in glucose-tolerant individuals. We hypothesised that the driving force for the changed postprandial glucose profiles after RYGB is rapid entry of glucose into the systemic circulation due to modified gastrointestinal anatomy, causing hypersecretion of insulin and other hormones influencing glucose disappearance and endogenous glucose production.