ODP166 Autoantibody Positivity and Random C-peptide Profile in Young Ethnic South Indian Population with Diabetes Mellitus

Abstract

Abstract The islet cell autoantibody and beta-cell reserve profiles of young-onset diabetes patients in India are not only heterogeneous but also differ from those in the rest of the world. We sought to assess 3 standard islet cell autoantibodies and random C-peptide in the young ethnic South Indian population with diabetes mellitus attending the Endocrinology OPD of our tertiary care. A total of 190 young diabetes patients aged between 12-30 years were screened for inclusion in the study. Known cases of gestational diabetes and those on diabetogenic drugs were excluded. Additionally, those with clinical features suggestive of pancreatic diabetes or maturity-onset diabetes of young (MODY), or any diabetes-associated syndromic disorders were also excluded. Finally, 138 eligible young diabetes patients were included in the study. The islet cell autoantibodies against glutamic acid decarboxylase (GAD), insulinoma-associated protein-2 (IA-2), zinc transporter (ZnT8)was measured by sandwich ELISA technique using a human GAD ELISA kit (Euroimmun, Germany), human IA2 ELISA kit (Euroimmun, Germany), human ZnT8 ELISA kit (RSR diagnostics, USA) respectively. Random C-peptide was measured with chemiluminescence immunoassay analyser Advia Centaur XP. Diagnosis of T1DM was based on the requirement of immediate insulin replacement therapy for hyperglycemia with or without acute-onset ketosis with random C-peptide (<0.6 ng/ml) with /without any of islet cell antibodies. Diagnosis of T2DM is based on the history of control of hyperglycemia with oral hypoglycemic agents with documentation of adequate beta-cell reserve (random C-peptide ≥ 0.6 ng/ml) while maintaining euglycemia. Based on the patient characteristics, treatment profile, islet cell antibody status, and beta-cell reserve as assessed by random C-peptide levels, 82 were classified as T1DM, and 48 were classified as T2DM. The rest 8 patients were categorized as unclassified diabetes. GAD antibody was seen in 54(66%) of 82 T1DM patients. Islet cell autoantibody negativity was documented in 21(26%) of T1DM patients. IA-2 and ZnT8 antibodies contributed to an additional 7(8%) to islet cell antibody positivity in T1DM patients. IA-2 antibody positivity was low and random C-peptide was undetectable in many cases of T1DM in our study and is probably due to prolonged duration of diabetes in many T1DM patients. Autoantibody positivity was seen in 4(8%) T2DM patients. These patients need to be followed up for possible evolution of latent autoimmune diabetes in adults.