Anomalous glucose and insulin responses in patients with insulinoma. Caveats for diagnosis.
Two patients with insulinomas had unusual glucose and insulin-secretory dynamics in response to prolonged fasting. In patient 1, low insulin values persisted throughout three separate supervised fasts without a steady rise in the insulin-glucose ratio. In patient 2, a rising insulin-glucose ratio during a fast returned to normal after a documented catecholamine surge following a transient hypoglycemic episode. While patient 1 had clearly elevated proinsulin values of 52% to 57%, patient 2 had a near-normal value of 23%. The diagnosis of an insulinoma can usually be made by obtaining simultaneous glucose and insulin values during a prolonged supervised fast. Rarely, however, anomalous results may be obtained during supervised fasts of patients with insulinoma, and a broader range of diagnostic tests will be required to establish the correct diagnosis.
D007516:Adenoma, Islet Cell / Q000175:diagnosis*; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D002395:Catecholamines / Q000097:blood; D005215:Fasting; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood; D007328:Insulin / Q000097:blood*; D007340:Insulinoma / Q000175:diagnosis*; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis*
D001786:Blood Glucose; D002395:Catecholamines; D007328:Insulin