Insulin autoimmune syndrome in a patient with vitiligo: a case report and review of literature.

Abstract

Background: Hirata syndrome is a rare cause of hypoglycemia characterized by high insulin levels and the presence of insulin autoantibodies. This case report aims to introduce Hirata syndrome as a cause of fasting hypoglycemia in a patient with autoimmune diseases, such as vitiligo. Notably, this is the first reported case of insulin autoimmune syndrome in Iran.

Case presentation: A 47-year-old Iranian female with no prior history of diabetes but a 10-year history of vitiligo experienced recurrent hypoglycemia symptoms as evidenced by neuroglycopenia and neurological symptoms. Biochemical evaluation revealed fasting hypoglycemia (35 mg/dL), hyperinsulinemia (> 2000 µIU/mL), elevated C-peptide (23 ng/mL), and negative sulfonylurea screening. Imaging studies excluded other causes, such as insulinoma. Considering the high level of insulin autoantibodies, the final diagnosis was insulin autoimmune syndrome. A small, frequent, low carbohydrate diet was considered as the treatment plan to relieve the hypoglycemic symptoms. The patient provided written consent authorizing the utilization of her medical data and the publication of this case study.

Conclusion: In patients without diabetes with autoimmune diseases, such as vitiligo, who present with hyperinsulinemic hypoglycemia accompanied by elevated C-peptide levels, insulin autoimmune syndrome can be considered as a diagnosis.