Depending on the operative trauma, insulin secretion is decreased until the 10th day after abdominal surgery. 2. The decreased insulin release is caused by a diminished discharge from the pancreatic beta cell during the second phase of insulin secretion (partially newly synthesized insulin). Insulin release during the early phase of insulin secretion (prestored insulin) is unchanged or even accelerated. 3. The glucose tolerance level is pathologically diminished until the 10th postoperative day.