BACKGROUND: The association of selective immunoglobulin A (IgA) deficiency with type 1 diabetes (T1D) remains unclear. This study was to evaluate serum IgA concentrations in Greek children and adolescents with T1D.METHODS: In two hundred individuals with T1D, serum IgA concentrations were quantitatively determined using nephelometry.RESULTS: Immunoglobulin A deficiency was detected in 6 (3.0%) of 200 patients who were subjected to immunological evaluation. Recurrent infections were not recorded, but human papilloma virus infection was clinically suspected and confirmed by laboratory examination in a 5-year-old girl. In regard to coincidence of selective IgA deficiency with autoimmune diseases, celiac disease was detected in a girl and juvenile idiopathic arthritis in a boy. Serum IgA concentrations differed significantly when patients were grouped according to age at the beginning of the study (P<0.001), age at diagnosis of T1D (P=0.015) and coincidence of celiac disease (CD) (P=0.038). However, when the age of the patients was adjusted, difference in serum IgA concentrations was not statistically significant despite CD was present or not. Moreover, serum IgA concentrations were positively correlated with serum IgG (P<0.001) and IgE (P=0.001) concentrations and negatively correlated with serum antigliadin antibody IgG (P=0.035) concentrations. There was no association or correlation of serum IgA concentrations with glycemic control.CONCLUSION: The prevalence of selective IgA deficiency in Greek children and adolescents with T1D is high (3.0%). The correlation of serum IgA concentrations with serum IgG, IgE and anti-gliadin antibody IgG concentrations needs further investigation.