Objectives The aim of this study was to investigate the mechanisms of the change in glucose metabolism after a pancreatoduodenectomy (PD). Methods Oral glucose tolerance tests were performed in 17 patients before and 1 month after a PD. The changes in plasma glucose and insulin concentrations, homeostasis model of insulin resistance, and insulinogenic index (beta-cell function) were analyzed. Two additional factors, gastric emptying function and plasma glucagon-like peptide-1 (GLP-1) concentration, that possibly affect perioperative glucose metabolism were also assessed. Results The plasma glucose and insulin concentrations were significantly lower after the operation, especially in preoperative diabetic patients. beta-Cell function did not change after the operation. On the other hand, insulin resistance became normal 1 month after the operation. The value of gastric emptying function after the operation was not statistically different in comparison with that before the operation. Postoperative plasma GLP-1 concentration was significantly higher than the preoperative value. Conclusions beta-Cell function is maintained after a PD, whereas the improvement of insulin resistance may cause a short-term transient improvement of the glucose metabolism after the operation. The significance of increased postoperative GLP-1 concentration remains an unsolved issue.
