“Insulinomas invariably occur only in the pancreas, distributed equally in the pancreatic head, body and tail". — Harrison 17/eInsulinomas are a β cell endocrinal tumur of the pancreas. Insulinomas are the most common pancreatic endocrine neoplasms. The symptoms are produced due to excessive secretion of insulin causing hypoglycemia Most of the insulinomas are solitary and benign, Only about 10-15% of insulinomas are malignant. (keep in mind that all other endocrine tumours of pancreas are usually malignant).Symptoms of insulinomaThe most common symptom is due to the effect of hypoglycemia on the central nervous system. These symptoms are - confusion, disorientation, visual difficulties, irrational behaviour, coma Other symptoms are due to increased secretion of catecholamines which includes sweating, tremor and palpitations. Classic diagnostic criteria is - Whipple's triad Signs and symptoms of hypoglycemia during fasting. Blood glucose below 2.8 mmol/L (50mg/dl) during symptomatic episodes. Relief of symptoms by intravenous administration of Glucose. The most useful diagnostic test and the only one indicated in almost all patients is demonstration Wasting hypoglycemia in the presence of inappropriately high level of insulin. The patient is fasted for 72 hrs or till the symptoms of hypoglycemia develop. When hypoglycemia develops, serum level of insulin is measured. A ratio of plasma insulin to glucose > 0.3 is diagnostic.Localization of the tumourOnce the diagnosis has been made, localization of the tumour is must for surgery. The most important examination for localization of tumour is intraoperative ultrasound, which can indentify pancreatic tumour in all cases. It is more sensitive than any other methodOther important methods of localization -High resolution CT and MN. Endoscopic ultrasound examination of pancreas. Selective arteriographyT/T - Surgical excision is the t/t of choice - Since most insulinomas are benign simple enucleation is done.