Objective: To review the published literature and perform a meta-analysis summarizing the evidence in support of an inverse association between type 1 diabetes and the atopic disorders: asthma, eczema, and allergic rhinitis in children.
Research design and methods: MEDLINE, Web of Science, and PubMed were searched to identify relevant studies. These were assessed on quality criteria, and odds ratios (ORs) and 95% CIs were calculated for each study from the reported prevalences of atopy in children with diabetes and in control children. Meta-analysis was then used to derive a combined OR and test for heterogeneity in findings between studies.
Results: Twenty-five studies were identified. Heterogeneity in the findings from different studies was evident but was considerably reduced when the asthma and rhinitis analyses were restricted to those studies judged to be of adequate design. The meta-analysis revealed an inverse association between asthma and type 1 diabetes, but the finding only attained significance when analysis was restricted to the studies of adequate design (OR 0.82, 95% CI 0.68-0.99). In this subset an association of similar magnitude was observed between eczema and type 1 diabetes (0.82, 0.62-1.10) although this failed to attain statistical significance, and heterogeneity between studies was still present. There was little evidence of an association between rhinitis and type 1 diabetes (0.97, 0.82-1.16) in this subset of studies.
Conclusions: Our analysis suggests that there is a small but significant reduction in the prevalence of asthma in children with type 1 diabetes, but the findings for the other atopic diseases are less conclusive.