Background and aim: Although insulinoma typically causes fasting hypoglycemia, postprandial hypoglycemia occasionally reported in these patients. We aimed to report a rare case of insulinoma who atmitted to outpatient clinic with postprandial hypoglycemia.
Case report: A 31-year-old woman was admitted to outpatient clinic with postprandial hypoglycemia. Capillary blood glucose levels were found 25 and 27 mg /dl during typical hypoglycemic symptoms such as blurred vision, palpitations, and weakness. These hypoglycemic episodes occured about 2 hours after eating and eliminated with sugary foods. The symptoms of hypoglycemia were decreased with diet modification and increase in meal frequency. After 6 months, hypoglycemic symptoms reappeared by exercise and delayed meals. Her physical examination was normal except hepatomegaly. Blood samples were taken after an overnight fast and serum blood glucose 91 mg/dl, insulin 5.64 uU/ml, kortizol 19.3 μg/dl, and c-peptide 1.14 ng/ml. Hb A1C, thyroid function tests, insulin like growht factor-1, anti- insulin antibody, liver and renal function tests were in normal range. Prolonged- 72 hours- fasting test was performed. After 56 hours, inappropriately high serum insulin concentration was showed during hypoglycemia. Endoscopic ultrasound showed 9,8 mm hypoechoic lesion in the head of the pancreas. Present findings suggested the presence of insulinoma. Operation was planned but not yet carried out.
Conclusions: Fasting hypoglycemia is the common clinical manifestation of insulinoma. However, postprandial hypoglycemia rarely observed in this situation. It is important to consider insulinoma as a cause of postprandial hypoglycemia.