ESPE Abstracts

Objective Insulin autoimmune syndrome (IAS) is a rare cause of hyperinsulinemic hypoglycemia in children. Methods We retrospectively analyzed the youngest diagnosed case of IAS in China, which presented as frequent spontaneous hypoglycemia. Results A 4-year-old boy with a height of 102.5 cm (-0.16 SD), weight of 18 kg (0.84 SD), and BMI of 17.13 kg/m2 (1.35 SD) was examined. He had no distinctive facial features or acanthosis nigricans. After a fasting test for 14 hours, his venous blood glucose level was 2.77 mmol/L, insulin level was 14.2 μIU/ml, C-peptide level was 0.23 ng/ml (insulin to C-peptide molar ratio >1), and β-hydroxybutyrate and free fatty acids were decreased; pancreatic magnetic resonance imaging showed negative results for both plain scan and enhanced images; whole-exome sequencing revealed negative results for genes associated with hyperinsulinemic hypoglycemia and multiple endocrine neoplasia type I (MEN1); prolonged oral glucose tolerance test indicated significantly increased insulin secretion (Table 1); diabetes autoantibody testing showed positive anti-insulin antibodies (54.38 COI) and glycated hemoglobin A1c level was at 5%. Based on these findings, a diagnosis of insulin autoimmune syndrome could be considered. Dietary adjustments were made to reduce carbohydrate intake, increase meal frequency while decreasing portion size per meal, and limit monosaccharide consumption during hospitalization resulting in reduced episodes of low blood sugar levels. Follow-up examination after six months showed decreased titers of anti-insulin antibodies (10.17 COI). However, intermittent episodes of low blood sugar continued outside the hospital due to failure to strictly adhere to dietary adjustments recommended by medical professionals. It is suggested that low-dose oral prednisone acetate should be administered daily at a dose rate of 2 mg QD until retesting for insulin autoantibodies three months later. Conclusion Hypoglycemia caused by hyperinsulinism is commonly diagnosed as congenital hyperinsulinism in children. It is important to pay attention to the form and pattern of hypoglycemic episodes in affected children. For postprandial hypoglycemia, caution should be taken for possible insulin autoimmune syndrome (IAS). Prolonged oral glucose tolerance test (OGTT) may not induce hypoglycemia but can detect increased insulin secretion. Screening for diabetes autoantibodies needs improvement, and secondary IAS should be ruled out after diagnosis. Dietary adjustments can be effective in treating IAS.