Co-occurrence of allergic sensitization and type 1 diabetes

Background. The mechanisms leading to abnormal immune regulation in type 1 diabetes and allergic diseases may be partly overlapping. If so, these diseases should co-occur more often than expected. We investigated this phenomenon in two contrasting socio-economic environments, Finland and Russian Karelia. Methods. We screened 413 Finnish children (of whom 147 had type 1 diabetes) and 244 Russian Karelian children (132 had type 1 diabetes) for total immunoglobulin E (IgE) levels and specific IgE against birch, cat, and egg albumen. In addition we analysed diabetes-related human leukocyte antigen (HLA) haplotypes and antibodies against hepatitis A virus (HAV) and recorded allergic diseases by a questionnaire in Russian Karelia. Results. In Russian Karelia 15% of the patients with type 1 diabetes, but only 4% of the control subjects had allergen-specific IgE (P=0.012). A similar difference was observed in the frequency of allergic symptoms. Co-occurrence of allergic sensitization and type 1 diabetes was associated with lack of HAV antibodies and was not seen in Finland where infections are less frequent than in Karelia. Conclusion. Our findings support the idea of common mechanisms in the pathogenesis of allergic diseases and type 1 diabetes, which may be particularly important in an environment with low penetrance of these diseases.