The incidence of type 2 diabetes in patients with bronchial asthma

Abstract

Abstract Background The effect of bronchial asthma on development of new-onset type 2 diabetes has not been studied. Aim The aim was to study the association of bronchial asthma and its severity with the incidence of type 2 diabetes after 5 years in patients without diabetes at the disease onset. Patients and methods A total of 200 consecutive patients with a physician diagnosis of bronchial asthma (120 not known to be diabetic and 80 known to have diabetes) presenting to the outpatient chest clinic in Kasr Alainy Hospital were included. Fasting blood glucose, 2h 75 g oral glucose tolerance test, glycated hemoglobin, and lipid profile were done. Spirometry, blood pressure, BMI, and other risk factors of diabetes were sought. Results Of the 120 nondiabetic patients, 30 patients met at least one criterion of prediabetes and 90 patients met at least one criterion of diabetes. Multivariable regression model demonstrated that forced vital capacity (FVC)%, maximal expiratory flow 75%, and inhaled bronchodilators are independent risk factors for elevated glycated hemoglobin, independent of inhaled or oral corticosteroids, family history, blood pressure, BMI, high-density lipoprotein, and triglycerides. Logistic multivariable regression model demonstrated that FVC% and forced expiratory volume in the first second % are independent risk factors for development of new-onset type 2 diabetes (hazard ratio for FVC%: 1.1589, 95% confidence interval: 1.0684–1.2571, P=0.0004; hazard ratio for forced expiratory volume in the first second %: 0.8754, 95% confidence interval: 0.8155–0.9396, P=0.0002). Conclusion The incidence of diabetes and prediabetes in patients with bronchial asthma who are not known to have diabetes at disease onset is 75 and 25%, respectively. Poor pulmonary function tests were independently associated with new-onset diabetes in such patients. This association is linked to the severity of asthma and not related to treatment.