Diagnosis of insulinoma in a patient with hypoglycemia without obvious hyperinsulinemia.

BACKGROUND: A 41-year-old Maltese woman with a 12-month history of severe, morning episodes of confusion, blurred vision and sweating was referred to a specialist center for evaluation of fasting hypoglycemia. She was not taking medication and did not report any prior personal or familial history of endocrinopathy or other relevant pathology. INVESTIGATIONS: Measurement of plasma glucose, insulin, C-peptide, and beta-hydroxybutyrate concentrations during a prolonged supervised fast; sulfonylurea screen; CT, MRI scan and endoscopic ultrasonography of the pancreas; calcium stimulation test; surgical exploration and intra-operative ultrasonography of the pancreas. DIAGNOSIS: Insulin-secreting lesion (insulinoma) in the tail of the pancreas. MANAGEMENT: The tumor was resected with cure of symptoms