title: Serological testing for coeliac disease in Type 1 diabetes mellitus: is immunoglobulin A level measurement necessary?
abstract: OBJECTIVE
  Immunoglobulin A (IgA) measurement is advocated when case finding for coeliac disease in patients with Type 1 diabetes mellitus. Currently, there is a paucity of contemporary studies assessing IgA deficiency in Type 1 diabetes. This study evaluates the prevalence of IgA deficiency in individuals with Type 1 diabetes, compared with patients with coeliac disease and control subjects. In addition, we evaluate whether routine IgA measurement is justifiable when case finding for coeliac disease in patients with Type 1 diabetes.
  
  
  METHODS
  All patients were assessed using IgA endomysial antibodies, IgA anti-tissue transglutaminase antibodies and total IgA levels. Altogether, 2434 individuals were tested: 1000 patients with Type 1 diabetes, 234 patients with coeliac disease and 1200 population control subjects. Definitive IgA deficiency was defined as total IgA levels < 0.07 g/l.
  
  
  RESULTS
  The prevalence of IgA deficiency was significantly more common in patients with Type 1 diabetes (0.9%, n = 9/1000; P = 0.036) and coeliac disease (1.29%, n = 3/234; P = 0.041) when compared with population control subjects (prevalence of 0.17%, 2/1200). No statistical difference between Type 1 diabetes and coeliac disease for IgA deficiency was identified (P = 0.87). Of patients in the group with Type 1 diabetes, 3.3% (33/1000) had coeliac disease, and of those only one patient had IgA deficiency leading to an antibody-negative presentation. Both IgA-deficient individuals within the population control subjects had normal duodenal biopsies and no relevant symptoms.
  
  
  CONCLUSIONS
  IgA deficiency is more common in Type 1 diabetes compared with population control subjects. Despite this, very few individuals with Type 1 diabetes and IgA deficiency appear to have villous atrophy on biopsy. These outcomes question the practice of routine IgA measurement when case finding for coeliac disease in patients with Type 1 diabetes.
authors: Gastroenterology and Liver Unit, Royal Hallamshire Hospital, Sheffield, UK. matthew.kurien@sth.nhs.uk
authors: M
authors: M
authors: Kurien
authors: J S
authors: JS
authors: Leeds
authors: A D
authors: AD
authors: Hopper
authors: G
authors: G
authors: Wild
authors: W
authors: W
authors: Egner
authors: S
authors: S
authors: Tesfaye
authors: M
authors: M
authors: Hadjivassiliou
authors: D S
authors: DS
authors: Sanders
mesh_terms: D000328:Adult; D002446:Celiac Disease / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000276:immunology* / Q000473:pathology; D004386:Duodenum / Q000473:pathology; D005260:Female; D005903:Gliadin / Q000276:immunology; D006801:Humans; D017098:IgA Deficiency / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D007070:Immunoglobulin A / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011503:Transglutaminases / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D005903:Gliadin; D011503:Transglutaminases