[Lack of hyperglycemic rebound after insulinoma removal: two case reports]

Two cases of anesthetic management for insulinoma were reported. The first patient, a 54-year-old man, suffering from repeated episodes of fasting hypoglycemia was scheduled for removal of insulinoma developed in the pancreas under isoflurane-nitrous oxide anesthesia. Preanesthetic plasma glucose concentration was 57 mg.dl-1. Glucose was continuously administered intravenously to maintain plasma glucose around 150 mg.dl-1. The second patient, a 65-year-old man suffering from several episodes of fasting hypoglycemia was scheduled for removal of insulinoma in the pancreas under isoflurane-nitrous oxide anesthesia. Preanesthetic plasma glucose was 103 mg.dl-1. An artificial pancreas was used to maintain plasma glucose at 140 mg.dl-1. In these patients, hyperglycemic rebound was not observed after removal of the insulinoma, and their perioperative courses were uneventful. Although relatively low immunoreactive insulin levels might relate, fine management of fluid and metabolism during preoperative period was thought as one of the reasons that hyperglycemic rebound did not occur in these patients. For the safe management of the patients with insulinoma, we recommend to maintain plasma glucose at the levels of mild hyperglycemia to prevent hypoglycemic episodes until the end of the removal.