title: Prevalence of Type 1 diabetes autoantibodies (GAD and IA2) in Sardinian children and adolescents with autoimmune thyroiditis.
abstract: OBJECTIVE
  Type 1 diabetes and autoimmune thyroiditis are common autoimmune diseases characterized by the presence of autoantibodies against tissue-specific components. Non-thyroid-specific autoantibodies are frequent in patients with autoimmune thyroiditis. The prevalence of Type 1 diabetes autoantibodies in patients with autoimmune thyroiditis is unknown.
  
  
  METHODS
  The prevalence of Type 1 diabetes autoantibodies (GAD and IA2) was analysed in 236 Sardinian children and adolescents with autoimmune thyroiditis. GAD and IA2 antibodies were measured at the time of the diagnosis of autoimmune thyroiditis and re-evaluated after 1 year in the children who were shown to be positive. Autoantibody prevalence was evaluated in 949 healthy age-matched controls.
  
  
  RESULTS
  The prevalence of GAD and/or IA2 antibodies was 8% in the children and adolescents with autoimmune thyroiditis and 4.1% in control subjects (P = 0.017). When Type 1 diabetes autoantibodies were separately analysed, the difference remained significant for IA2 (3.39% in autoimmune thyroiditis vs. 1.16% in control subjects, P = 0.012), but not for GAD (5.1% in autoimmune thyroiditis vs. 3.79% in control subjects, P = 0.367). Seven of 10 children with autoimmune thyroiditis and detectable Type 1 diabetes autoantibodies at the diagnosis remained positive after 1 year. In the course of 2 years of follow-up, two patients who were positive for Type 1 diabetes autoantibodies at the time of diagnosis of autoimmune thyroiditis developed diabetes.
  
  
  CONCLUSIONS
  This is the first study reporting the prevalence of Type 1 diabetes autoantibodies in a selected cohort of genetically homogeneous children and adolescents with autoimmune thyroiditis. The main finding was that the prevalence of Type 1 diabetes autoantibodies and of newly diagnosed Type 1 diabetes in patients with autoimmune thyroiditis was significantly higher than that observed in the general paediatric population, suggesting that children with autoimmune thyroiditis are at increased risk of developing Type 1 diabetes.
authors.affiliation: Paediatric Endocrine Unit, Microcitemico Hospital, University of Cagliari, Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Pilia
authors.forename: M R
authors.initials: MR
authors.lastname: Casini
authors.forename: V M
authors.initials: VM
authors.lastname: Cambuli
authors.forename: A
authors.initials: A
authors.lastname: Ibba
authors.forename: P
authors.initials: P
authors.lastname: Civolani
authors.forename: P
authors.initials: P
authors.lastname: Zavattari
authors.forename: M
authors.initials: M
authors.lastname: Incani
authors.forename: P
authors.initials: P
authors.lastname: Mossa
authors.forename: M G
authors.initials: MG
authors.lastname: Baroni
authors.forename: S
authors.initials: S
authors.lastname: Mariotti
authors.forename: S
authors.initials: S
authors.lastname: Loche
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000145:classification / Q000276:immunology*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000145:classification / Q000276:immunology*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D017027:Protein Tyrosine Phosphatases / Q000145:classification / Q000276:immunology*; D013967:Thyroiditis, Autoimmune / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D017027:Protein Tyrosine Phosphatases; D005968:Glutamate Decarboxylase