The aim of this study was to assess the association between pancreatic and thyroid autoimmunity (TA) and determine impact of thyroid antibodies on statural growth. Seventy-two children with type 1 diabetes mellitus (TIDM) and no clinical evidence of thyroid disorders were evaluated: glycated haemoglobin (A1c), thyroid peroxidase antibodies (TPOAb), glutamic acid decarboxylase antibody (GADA), tyrosine phosphatase antibodies (IA2A), and thyroid-stimulating hormone (TSH). The score of standard deviation for height (SDS) was calculated. There were 72 patients, 38 (52.7%) boys and 34 (47.2%) girls, with a mean age of 10.89 +/- 4.26 years and a mean duration of T1DM of 3.41 +/- 2.56 years. TPOAb were present in 23.6% of patients; 12.5% of subjects were positive for GADA and 41.6% for IA2A. Patients with TA had more prevalent GADA and IA2A (23.5% vs. 9%, p < 0.001, and 58.8% vs. 36.3%, p < 0.001, respectively). A1c was higher in patients with TA (9.7% +/- 2.05% vs. 8.6% +/- 2.11%, p = 0.05). TA was associated with lower SDS (0.26 vs. 0.98, p = 0.043). TSH was higher in patients with TA (3.39 vs. 2.15 microU/mL, p < 0.05). Logistic regression analysis revealed that a negative SDS for height was independently associated with duration of diabetes (p = 0.049) and TSH (p = 0.027) but not with birth weight, A1c, and TPOAb. In conclusion, TA was found in 23.6% TIDM children. Patients with TA had significantly higher prevalence of GADA and IA2A and significantly higher A1c vs. patients without TA. Our data suggest significant association between TA and height in children with T1DM. SDS was independently associated with diabetes duration and TSH.