May T1 diabetes mellitus protect from asthma?

Background: Type 1 diabetes mellitus (T1DM) may be associated with allergy. It was previously reported that >20% of children with T1DM had allergic rhinitis (AR), but none was asthmatic. This finding was surprising as allergic rhinitis is frequently associated with asthma and asthma prevalence is about 10% of the general paediatric population. Thus, it was hypothesized that T1DM could protect from asthma.

Objectives: The aim of this preliminary study was to evaluate the pulmonary function and the response to bronchodilation testing in children, suffering from T1DM with associated AR, comparing them with a control group of children with AR alone.

Methods: Twenty children with T1DM and AR were compared with 59 children with AR alone; spirometry and bronchodilation testing were performed in all patients.

Results: There were no statistically significant differences in both "at baseline" and after bronchodilation testing about FVC, FEV1, and FEF25-75 values. However, changes in "post-bronchodilator" values of FEF25-75 (ΔFEF25-75) were significantly higher in children with AR alone than in children with T1DM and AR (p=0.04).

Conclusions: This preliminary study could sustain the hypothesis that T1DM in children suffering also from AR might exert a protective effect of preventing the possible evolution in asthma.