Exogenous Insulin Antibody Syndrome: An Overlooked Cause of Severe Hypoglycemia and Insulin Resistance in a Patient With Type 2 Diabetes Treated With Insulin

We report an 80-year-old man with type 2 diabetes who presented with life-threatening hypoglycemia (36 mg/dL) and coma, requiring high-dose insulin (74 units/day). Exogenous insulin antibody syndrome (EIAS) was suspected due to his glycemic instability and high insulin requirements. Subsequent testing confirmed elevated insulin antibodies (8.7 U/mL). Switching insulin analogues (to 32 units/day) promptly achieved stable glycemic control. This case highlights that EIAS, an under-recognized cause of unpredictable glycemia in insulin-treated diabetes, should be considered in patients with severe hypoglycemia and high insulin requirements. Modifying the insulin regimen is key for diagnosis and treatment.