Pancreatic Insulinoma Presenting with Episodes of Hypoinsulinemic

We report a rare case of pancreatic islet cell tumor (insulinoma) presenting with hypoinsulinemic hypoglycemia in an elderly man by laboratory diagnosis. Insulinoma is characterized by spontaneous fasting hypoglycemia and its diagnosis relies on inappropriately increased insulin levels during episode of hypoglycemia and/or high insulin/glucose ratio. This report highlighted that the diagnosis of insuli-noma or islet cell tumor cannot be excluded by hypoinsulinemic hypoglycemia absolutely. Further an-alytic measurements for cross-reacting insulin or determination of proinsulin or insulin-like growth fac-tor levels should be considered when highly suspected insulinoma or documented pancreatic nodule was found in patients with hypoglycemic episode. ( J Intern Med Taiwan 2008; 19: 432-436