Abstract 161: Prevalence of auto-antibodies in children and adolescents with type 1 diabetes, and their association with the clinical parameters

Objective: To determine the prevalence of disease specific auto-antibodies: anti-glutamic acid decarboxylase (anti-GAD), anti-zinc transporter (anti-ZnT8), anti-islet cell (AICA), insulin autoantibody (IAA), and other organ specific autoantibodies: anti-thyroid peroxidase (anti-TPO) and IgA anti-tissue transglutaminase (anti-tTG) in children with T1D. To evaluate correlation between antibodies positivity and clinical parameters related to T1D. Methods: 300 insulin requiring children, with onset of diabetes between 6 months and 18 years of age, attending the T1D clinic of our institute between Jan-19 and Apr-22, were enrolled. T1D was diagnosed as per the ISPAD criteria, coupled with documentation of insulinopenia (fasting C-peptide <0.6 ng/ml). Children with secondary, neonatal, monogenic and drug induced diabetes were excluded. 272 patients were included in the analysis. Continuous and categorical data are presented as mean ± SD and frequency (%), respectively. Pearson's coefficient was used to determine correlation between the various parameters. Results: Mean age of our cohort was 10.5 ± 4 years, with 53.3% girls. Mean age at diagnosis was 7.4 ± 3.9 years, with 3.1 ± 3.2 years being the mean duration of diabetes.12.5% children were hypothyroid and 15.1% had celiac disease. Anti-GAD, anti-ZnT8, AICA and IAA antibodies were present in 58.5%, 32.3%, 32% and 16.9% children, respectively. 22.1% patients were antibody negative. At least two antibodies were present in 27.6%. Three antibodies were present in 11%, and 3.3% had all four auto-antibodies positive. The presence of anti-TPO and IgA anti-tTG was seen in 28.3% and 13.6%, respectively. Age at diagnosis positively correlated with anti-GAD positivity, and negatively correlated with IAA positivity. Duration of diabetes negatively correlated with T1D antibodies positivity, multiple antibodies positivity, and anti-GAD, anti-ZnT8 and AICA positivity. There was no gender difference observed. Presence of nephropathy and retinopathy negatively correlated to anti-GAD positivity. Anti-TPO positivity was more common in the female children. Presence of IgA anti-tTG negatively correlated with age of T1D onset, and positively correlated to duration of diabetes. Conclusion: Children diagnosed at younger age are more likely to be anti-GAD positive, while those diagnosed at older age are more likely to demonstrate IAA positivity. Positivity for multiple auto-antibodies, and anti-GAD, anti-ZnT8 and AICA decreases with increasing duration of diabetes. Girls are more likely to develop anti-TPO positivity, while IgA anti-tTG positivity is seen in older children and those with longer duration of diabetes.