Association of insulin resistance with bronchial hyperreactivity

BACKGROUND Several epidemiologic studies showed the significant association of insulin resistance with asthma. OBJECTIVE The aim of this study was to evaluate the association of insulin resistance with airway hyperresponsiveness (AHR) in adult population. METHODS 1,058 subjects who visited to the Seoul National University Hospital Gangnam Center from October 2007 to January 2009 for a routine health check-up were enrolled. All subjects completed a questionnaire, anthropometric measurements such as body mass index (BMI) and waist circumference, blood tests, pulmonary function test, and methacholine bronchial provocation test (MBPT). Insulin resistance was estimated from the homeostasis model of assessment of insulin resistance (HOMA-IR). RESULTS Thirty-three subjects (3.1%) had AHR based on MBPT. The subjects with AHR had higher BMI, waist circumference, and HOMA-IR than those without AHR (p < 0.001, p = 0.003, and p = 0.002, respectively). In case of men, fasting insulin level and HOMA-IR had significant correlation with forced expiratory volume in 1 second (%) (r = -0.1440, p = 0.011, and r = -0.1156, p = 0.042, respectively). Fasting insulin level and HOMA-IR were higher in men with AHR than in those without (p = 0.046 and p = 0.040, respectively). In binary logistic regression analysis after adjustment for age, HOMA-IR was the significant risk factor for AHR in men (HOMA-IR: odds ratio [OR], 3.21; 95% confidence interval [CI], 1.00-10.30). In case of women, fasting insulin, glucose level, or insulin resistance had no significant correlation with lung function. BMI, waist circumference, and HOMA-IR were significantly higher in women with AHR than in those without (p = 0.001, p = 0.011, and p = 0.010, respectively). In binary logistic regression analysis after adjustment for age, BMI and HOMA-IR were the significant risk factors for AHR in women (BMI: OR, 2.20; 95% CI, 1.23-3.82; insulin resistance: OR, 1.05; 95% CI, 1.00-1.09). CONCLUSION Insulin resistance was significantly associated with bronchial hyperreactivity, which is the most characteristic feature of asthma.