A 50-year-old woman was hospitalized for fainting caused by hypoglycemia. Her blood glucose level was low (40 mg/dL), immunoreactive insulin was 16.9 μU/mL, and C-peptide level was high (4.8 ng/mL). Computed tomography and magnetic resonance imaging revealed a 7-mm tumor in the uncinate process of the pancreas. A selective arterial calcium injection test indicated an increase in the superior mesenteric artery. Insulinoma of the uncinate process of the pancreas was diagnosed, and tumor enucleation was planned using an artificial pancreas for intraoperative and postoperative blood glucose control. Hypoglycemia (blood glucose, 38 mg/dL) was observed from the onset of surgery. An artificial pancreas cannot be used if the blood glucose level is ≤ 70 mg/dL; thus, continuous glucose infusion was administered. The sudden rise in blood glucose prompted insulin infusion from the device, causing hypoglycemia. Controlling blood glucose levels is challenging when introducing the artificial pancreas. However, altering the device's blood glucose control algorithm controlled the fluctuating blood glucose level, and, intraoperative average blood glucose was raised to 94.8 ± 21.1 mg/dL, thereby avoiding hypoglycemia, that is, a blood glucose level of ≤ 70 mg/dL. We report a case in which an artificial pancreas was used for glycemic control during surgery for an insulinoma.
