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

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.

© 2025. The Author(s).