T-helper 1 (Th1) and T-helper 2 (Th2) cells play a key role in the pathogenesis of type 1 diabetes and atopic diseases, respectively. Because the Th1 and Th2 cells mutually inhibit each other (1), it has been speculated that patients with type 1 diabetes have a lower predisposition to atopy. However, the findings have been conflicting (2). In contrast, there seems to be no report regarding the relationship between atopy and type 2 diabetes.
We examined the relationship between allergic rhinitis and levels of fasting plasma glucose (FPG). The subjects were 10,093 male workers who had not taken medication other than that for rhinitis. Information regarding current medication, lifestyle habits, and past and present illnesses was obtained by a self-reported questionnaire. The prevalences of rhinitis were 11.2, 10.8, 9.9, 7.8, and 6.7% in subjects with FPG levels of <90, 90–99, 100–109, 110–125, and ≥126 mg/dl, respectively. Multiple regression analysis revealed that rhinitis was associated negatively with the amount of smoking (P < 0.001), age (P = 0.004), leukocyte counts (P = 0.013), systolic blood pressure (P = 0.034), frequency of exercise (P = 0.041), and FPG (P = 0.0478) and was associated positively with BMI (P = 0.015). Next, we calculated the odds ratio of the prevalence of rhinitis in subjects with FPG levels of ≥110 mg/dl against those with FPG levels of <110 mg/dl. The unadjusted odds ratio was 0.663 (P = 0.0008); the odds ratio adjusted for age, BMI, amount of smoking, and frequency of exercise, was 0.748 (P = 0.0231) and was 0.791 (P = 0.070) after being further adjusted for systolic blood pressure and leukocyte counts.
The results suggest that subjects with higher levels of FPG had a lower prevalence of rhinitis. FPG, smoking, blood pressure, and leukocyte counts, which rhinitis had a negative association with in this study, are all associated with inflammation (3,4). Allanore et al. (5) also indicated a decreased prevalence of atopy in subjects with rheumatoid arthritis, an autoimmune and inflammatory disease. Therefore, chronic inflammation might prevent rhinitis, although this mechanism was unclear. Further cross-sectional and prospective studies are needed to confirm the present findings.
Acknowledgments
No potential conflicts of interest relevant to this article were reported.
