Type 1 diabetes mellitus is frequently associated with autoimmune thyroid disease (AITD) and both diseases share similar risk of the HLA class II genotypes. 285 diabetic children (158 boys and 127 girls) aged 0 to 18 years esere screened for thyroid autoimmunity using autoantibodies against thyroid peroxidase (TPO) and thyroglobulin (TG). The HLA-DQAl, -DQBl genotype was investigated by the polymerace chain reaction with set sequence-specific primers (PCR-55P) in all children of the study group. The levels of risk authors calculated as odds rado (OR) and 95% confidence interval. Repeated Pozitivity of TPO and/or TG autoantibodies was found in 45/285 diabetic children (15.8%) and the prevalence rate was significantly higher in girls than in boys (27% vs. 7%, P < 0.001). The susceptibility of thyroid autoimmunity in diabetic children was negatively associated with the Presence of DQBl*05xx alleles (DQBl*0501, *0502, *0503) conferring the OR 0.2, CI 95 % 0.05 - 0.85, P < 0.03, and Positively associated with HLA-DQBl*0302 (OR 2.6, CI 95 % 1.1- 6.2, P < 0.04). The high prevalence of thyroid autoimmunity found in the group of diabetic children emphasises the need for their regular screening.

        Key words: autoimmune thyroid disease, autoimmune thyroiditis, anti-TPO, anti-TG, HLA class H molecules and genetic risk, screening