A Case of Exogenous Insulin Autoimmune Syndrome: A Case Report.

Insulin autoimmune syndrome (IAS) is a rare cause of endogenous hyperinsulinemic hypoglycemia triggered by insulin autoantibodies. Through extensive research on IAS in recent years, it has been revealed that the use of exogenous insulin by diabetic patients can result in clinical manifestations similar to those of IAS. This phenomenon is known as exogenous IAS (EIAS). This article describes a case of a patient with EIAS who presented with atypical clinical manifestations. The patient, a middle-aged female with a 17-year history of type 2 diabetes, had been using Insulin Aspart 30 Injection for almost 10 years. She developed severe hyperinsulinemia, low C-peptide levels, positive insulin antibodies, poor postprandial glycemic control, and occasional autonomic nervous system symptoms such as hunger, palpitations, fatigue, and excessive sweating. Despite these symptoms, hypoglycemia was not detected. Switching the type of insulin for two weeks resulted in a significant reduction in insulin dosage, leading to stabilization of fasting and two-hour postprandial blood glucose levels within the target range. This article aims to alert medical professionals about diabetic patients who have hyperinsulinemia, insulin antibodies, and difficulty controlling blood sugar due to EIAS. It is crucial to prevent missed diagnoses, misdiagnoses, and potentially unnecessary surgical interventions through increased awareness.