ABSTRACT
Insulin autoimmune syndrome is an uncommon cause of hypoglycemia. According to the type of antibody, it can be classified as caused by insulin or insulin receptor autoantibodies. Generally, insulin autoimmune syndrome develops following exposure to exogenous insulin or sulfhydryl medications, although insulin or insulin receptor antibody may also occur spontaneously. We treated a 54-year-old woman who developed spontaneous hypoglycemia. The patient had repeated hypoglycemia despite the infusion of dextrose solution. Her serum insulin, c-peptide, and insulin autoantibody were elevated, even during the hypoglycemic periods. Insulin receptor autoantibody and HLA-cw4/B62/DR4 were positive. After steroid and diazoxide treatment, the hypoglycemic symptoms improved gradually. No further hypoglycemic episodes occurred after tapering the medication over 1 year. We present a case of insulin autoimmune syndrome with positive insulin and insulin receptor autoantibodies.