Insulin autoimmune syndrome in a 3-year-old boy: the youngest to date in China and a narrow review.

Abstract

Background: Insulin autoimmune syndrome (IAS), characterized by endogenous hypoglycemia associated with insulin autoantibodies, is a rare cause of hypoglycemia in pediatric patients. Here, we report a case of the youngest patient with IAS in China, and summarize the clinical characteristics of the disease through a narrow review of pediatric cases.

Case presentation: A 3-year-10-month-old Chinese boy presented with unconsciousness. Initially, he was misdiagnosed with hyperinsulinemic hypoglycemia (HH) due to non-ketotic hypoglycemia. Whole exome sequencing (WES) was negative, and no pancreatic space-occupying lesions were identified. He continued to have intermittent episodes of symptomatic hypoglycemia. During an extended oral glucose tolerance test (OGTT), his insulin to C-peptide molar ratio was greater than 1, and anti-insulin antibodies (IAAs) measurements were as high as 54.38 COI (normal range 0-1 COI). High-resolution human leukocyte antigen (HLA) test showed a DRB1*08:03/*12:02 genotype. He was eventually diagnosed with IAS. Hypoglycemic episodes were not observed as long as the patient adhered to the low and frequent carbohydrate diet. Six months later, the patient's anti-insulin antibody had decreased to 10.17 COI, and mildly symptomatic hypoglycemia occasionally occurred in the case of noncompliance with the diet. Based on 11 studies from a literature review and our own case, a total of 12 pediatric patients were analyzed. Most of these patients presented with unconsciousness initially and their episodes of hypoglycemia do not follow a definitive pattern. Adjustments in diet serve as an effective intervention, and spontaneous remission is relatively common.

Conclusion: When differentiating the causes of HH in pediatric patients, IAS should not be overlooked. Elevated levels of IAAs and an inappropriate insulin to C-peptide molar ratio during an extended OGTT are critical indicators.

Clinical trial number: Not applicable.