A 45-year-old woman presented with a 3-year history of confusion and seizures refractory to anticonvulsant therapy. A biochemical diagnosis of excess endogenous insulin production was established by a serum glucose level of 46 mg/dL, serum insulin level of 4 μIU/mL, C-peptide level of 0.9 ng/mL, proinsulin level of 19.9 pmol/L, and a negative sulfonylurea screen. Her neuroglycopenic symptoms were relieved by intravenous glucose administration. She had no history of peptic ulcer disease (serum gastrin level of <25 pg/mL), nipple discharge, or hypercalcemia (serum calcium level of 9.6 mg/dL). By preoperative transabdominal ultrasound, a 1-cm hypervascular mass was identified in the body of the posterior pancreas (Figure 1). She was taken to the operating room for enucleation of a well-circumscribed 7-mm insulinoma that was confirmed by immunohistochemical staining. No additional masses were identified intraoperatively by palpation. Her intraoperative serum glucose levels rebounded to 99 mg/dL without glucose infusion.