Background: A rare form of hypoglycemia called insulin autoimmune syndrome (IAS) occurs when someone who has never been exposed to endogenous insulin develops insulin auto antibodies. As far as our knowledge goes, only 30 cases have been reported in India. Here we report one case of insulin autoimmune syndrome diagnosed and managed in our hospital.

Case Presentation: We present a case of a 68 year-old male who presented with recurrent episodes of post-prandial hypoglycemia. On biochemical evaluation, he was found to have hyper insulinaemic hypoglycemia. Localization studies with CT abdomen were negative for insulinoma. The diagnosis was confirmed by elevated blood levels of insulin auto antibodies. The patient was treated with frequent low carbohydrate meals and high dose corticosteroids. The patient’s condition improved, and able to maintain euglycemia on a low dose of corticosteroids.

Conclusion: IAS is a rare endogenous cause of hyper insulinaemic hypoglycemia. It should be suspected in patients presenting with post prandial hypoglycemia, with high insulin and C peptide levels.