Clopidogrel-Induced Insulin Autoimmune Syndrome: Efficacy of Glucocorticoid Therapy and Continuous Glucose Monitoring

Insulin autoimmune syndrome (IAS) is a rare cause of spontaneous hyperinsulinemic hypoglycemia characterized by elevated insulin autoantibody (IAA). Over half of IAS cases involve exposure to sulfhydryl group-containing medications or their active metabolites, with clopidogrel being an uncommon trigger. We report a case of clopidogrel-induced IAS (CIAS) treated with glucocorticoid and managed by continuous glucose monitoring (CGM) during follow-up.

A 77-year-old man developed recurrent severe hypoglycemia events after receiving clopidogrel for six months. Laboratory investigations showed significantly elevated serum insulin levels (peak: 1,452.52 mIU/L; normal range: 1.9-23.0 mIU/L) and a high IAA titer of 37.0 COI (>1.1 COI, positive). Following the exclusion of other potential causes of hypoglycemia, IAS was diagnosed. Consequently, clopidogrel was discontinued, and combination therapy incorporating prednisolone was initiated. During the 10-month follow-up, insulin levels declined to 8.09 mIU/L with IAA titers decreasing to 1.35 COI. Analysis of CGM data demonstrated a transition from glycemic fluctuations to stabilization.

This single-patient case report highlights the significance of identifying CIAS as a rare adverse effect of a drug, the effectiveness of glucocorticoid therapy, and the role of CGM in IAS management.