Prevalence of atopy in children with type 1 diabetes mellitus in central Taiwan

Atopic diseases, including asthma, eczema and allergic rhinitis, are characterized by a chronic inflammatory reaction mediated by T helper 2 (Th2) cells, while type 1 diabetes mellitus (T1D) is mediated by T helper 1 (Th1) cells. The 'balance' between Th1 and Th2 cells appears to be vitally important. Hence, it is a plausible hypothesis that the prevalence in Th2-mediated disease would be lower in patients with Th1-mediated disease. The aim of this study was to compare the prevalence of atopic diseases between children with T1D and age-matched controls, and investigate possible factors that influence the prevalence of atopic disease.

Parents of children with T1D in Taichung Veterans General Hospital were requested by pediatricians to complete the International Study of Asthma and Allergies in Childhood questionnaire on the prevalence of atopic diseases. Responses were compared with an age-matched control group.

Questionnaires were evaluated from 100 T1D patients and 194 controls. After age-matching, the questionnaires of 54 T1D patients were included. Symptoms of asthma, allergic rhinitis and eczema were reported less often in the group of children with T1D compared with the control group (wheeze with exercise, p=0.044; nasal symptoms with itching eyes in the past 12 months, p=0.048; nasal allergy ever, p=0.038; skin rash in the past 12 months, p=0.044). In addition, the proportion of T1D patients with any asthmatic symptom (such as wheezing once in life, wheezing in the past 12 months, wheezing with exercise and dry cough at night in the past 12 months) was significantly lower than in controls (20.4% vs 36.6%, p=0.036).

These results indicate that patients with T1D have a lower prevalence of atopic symptoms, especially asthma, which is consistent with the Th1/Th2 polarization concept. Environmental factors are another direct influence on the development of atopy in T1D patients.