ESPE Abstracts

Instruction: Type 1 diabetes mellitus is closely associated with several autoantibodies such as GAD autoantibody, insulin autoantibody, islet cell cytoplasmic antibody (ICA), IA-2 Autoantibody, ZnT8 autoantibody., ICA test is being replaced by IA-2, ZnT8 is still not available in Korea. The implement of IA-2 autoantibody testing in Korea marks a significant diagnostic advancement. The aimof this study is evaluating clinical significance and diagnostic utility of IA-2 autoantibodies in Korean pediatric diabetes patients, comparing it with other autoantibodies to improve diagnostic accuracy and understand prevalence in Korean.

Methods: We retrospectively analyzed 83 pediatric and adolescent diabetes patients under the age of 19, who were diagnosed and followed up at single tertiary hospital from January 2022 to April 2024. All patients were tested for GAD autoantibodies, insulin autoantibody. Of these, 38 patients underwent only ICA, 30 patients underwent only IA-2 and 15 patients underwent both ICA and IA-2.

Result: Among 83 subjects, type 2 diabetes were 59.0%(n = 49) and type 1 diabetes were 41.0% (n = 34). The overall rate of autoantibody positivity at initial measurement in type 1 DM was 76.5% (n = 26). Only one patient (2.9% in T1DM) had 3 positive result for autoantibodies Positive of GADA, IAA, ICA/IA-2. 14 patients (41.1 %in T1DM) had 2 positive result for autoantibodies. 10 patients (29.4%) had 1 positive autoantibody. When ICA was positive, IA-2A results were invariably positive; however, when IA-2A was positive, positive predictive value of ICA was 33.3%. In TIDM patients, IA-2A was positive in 70% of the cases, whereas GADA was positive in 54.2%, gray zone in 11.4% and IAA revealed positive in 28.6%. when GADA was positive, the IA-2 positive rate was 75%, when IA-2 was positive, the GADA positive rate was 64.2%. when GADA was negative, IA-2A negative rate was 33.3%, and when IA-2A is negative, GADA negative rate was also 33.3%. Patients with positive IAA were diagnosed at the youngest average age (P = 0.0036) and the lowest average c-peptide levels in both urine and fasting serum. Conversely, Patients with negative autoantibodies showed the highest mean age, Hba1c, glycated albumin.

Conclusion: we analyzed autoantibodies in pediatric diabetes. These findings underscore the complementary nature of GADA and IA-2A testing in diagnosing T1DM, particularly given the varied presentation and predictive value of different autoantibodies. Especially ICA test can be replaced with IA-2A. Comprehensive autoantibody screening is allowing for better stratification of patients based on their autoantibody profiles.