Insulin autoimmune syndrome: A rare cause of spontaneous hypoglycaemia in non-diabetic individuals

Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycaemia, characterised by recurrent hypoglycaemic episodes secondary to insulin autoantibodies in individuals who are not exposed to exogenous insulin. We are reporting a case of IAS in a 64-year-old gentleman, who presented with predominant postprandial hypoglycaemic episodes. On biochemical evaluation, he was found to have hyperinsulinemic hypoglycaemia. Localisation studies with MRI abdomen and endoscopic ultrasound (EUS) were negative for pancreatic tumour. Tests sent for insulin antibody levels were elevated. The patient was treated with frequent meals, acarbose and glucocorticoids. Patient condition improved and did not experience hypoglycaemia on follow-up.