Introduction: Type 1 diabetes mellitus (T1DM) is associated with other autoimmune disorders that are characterized by presence of organ-specific autoantibodies. The present study was undertaken to assess the prevalence of organ-specific autoantibodies among newly diagnosed T1DM subjects of India and to study its relationship with glutamic acid decarboxylase antibody (GADA). We also compared the clinical and biochemical parameters in GADA-positive and -negative T1DM subjects.Methods: In a hospital-based cross-sectional study, we studied 61 patients with newly diagnosed T1DM ≤ 30 years of age. T1DM was diagnosed on the basis of acute onset of osmotic symptoms with or without ketoacidosis, severe hyperglycaemia [blood glucose > 13.9 mmol/l (>250 mg/dl)] and insulin requirement from the onset of diabetes. Subjects were screened for autoimmune thyroid disease (thyroid peroxidase antibody [TPOAb]), celiac disease (tissue transglutaminase antibody [tTGAb]), and gastric autoimmunity (parietal cell antibody [PCA]).Results: Of the 61 subjects, more than one-third (38%) had at least one positive organ-specific autoantibody. In particular, 13 (21.3%) were found to be positive for TPOAb, nine (14.8%) were positive for tTGAb and 11 (18%) were positive for PCA. GADA was positive in 15 (25%) subjects. The frequency of TPOAb tended to be higher in patients who had GADA positivity compared with those with no circulating GADA (40%vs.15.2%;p=0.07). Subjects positive for GADA were also more likely to be PCA positive compared with those who were GADA negative (40vs.10.9%,p=0.02). There were no differences in frequency of diabetic ketoacidosis, body mass index, hemoglobin A1C (HbA1c), insulin requirement or fasting C-peptide in GADA-positive and -negative patients.Conclusion: We support the recommendation for regular screening of organ-specific autoantibodies, in particular TPOAb, tTGAb and PCA in all patients with T1DM. Detection of these autoantibodies at onset may prevent complications associated with delayed diagnosis of these disorders. We also conclude that there is higher frequency of TPOAb and PCA in GADA-positive T1DM patients as compared to negative ones. However, patients with positive GADA had similar clinical and biochemical parameters compared to GADA-negative subjects. Lastly, low GADA positivity in our study cohort as compared to Western populations suggests the heterogenous nature of T1DM in the Indian population.