Aims/hypothesis: Coeliac disease is more prevalent among patients with Type I (insulin-dependent) diabetes mellitus and coeliac disease-related antibodies have been reported to increase in frequency in their first-degree relatives. Our aim was to find out if coeliac disease is more common among siblings of children with Type I diabetes than in the normal population.
Methods: IgA endomysium antibodies were measured by indirect immunofluorescence in 550 subjects (mean age 11.8 years, range 3.1-26.9 years) with a sibling with Type I diabetes. We performed jejunal biopsy on as many subjects with positive antibodies as agreed. HLA-DQB1 genotyping was done in 427 subjects.
Results: Endomysium antibodies were positive in nine subjects (1.6 %). Jejunal biopsy was diagnostic for coeliac disease in five out of seven patients. An additional patient with coeliac disease, one already on a gluten-free diet, was identified by questionnaire. The prevalence of coeliac disease was 1.1 %. Five of six patients with coeliac disease had HLA-DQB1*02 allele, compared with 118 of 421 of those without coeliac disease (p = 0.009). The sixth patient was positive for HLA-DQB1*0302 allele, which was also found in 241 of 421 of those without coeliac disease (p = 0.4).
Conclusion/interpretation: We found the prevalence of coeliac disease among siblings of children with Type I diabetes to be similar to figures reported from recent population-based studies and to be correlated with the prevalence of coeliac disease associated HLA-DQB1 alleles. We propose that routine screening for coeliac disease among all first-degree relatives of patients with Type I diabetes is not warranted.