A study of the relationship between pulmonary function tests and both fasting plasma glucose and glycated hemoglobin levels among asymptomatic cigarette smokers

Tobacco smoke has been recognized as an independent risk factor for chronic obstructive pulmonary disease and diabetes mellitus type 2. To investigate the association between the presence of airflow obstruction in pulmonary functions and both fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) levels among asymptomatic cigarette smokers. Pulmonary function indices via spirometry and both FPG and HbA1c levels were altogether assessed in 300 apparently healthy participants attending health checkup clinic. Participants were stratified according to their smoking status into group I, which included 150 current and former cigarette smokers (ever smokers), and group II, which included 150 participants with no history of smoking (never smokers). FPG and HbA1c% were significantly higher among group I compared with group II (P=0.001 and 0.002, respectively). However, percent of forced expiratory volume in 1 s/forced vital capacity ratio less than 70% was statistically more prevalent among group I compared with group II (17.3, 6.7%, respectively, P=0.042), and the odds ratio (OR) of its occurrence increased with FPG more than or equal to 100 mg/ dl [OR=2.91; 95% confidence interval (CI)=1.62–4.01], HbA1c more than or equal to 5.6% (OR=2.07; 95% CI=0.12–0.77), age more than or equal to 50 years (OR=2.85; 95% CI=1.69–3.99), smoking index more than or equal to 25 pack-years (OR=3.11; 95% CI=1.85–3.66), and BMI more than or equal to 25 kg/m2 (OR=2.33; 95% CI=0.06–0.84). Risk of chronic obstructive pulmonary disease is increased among asymptomatic current or former cigarette smokers, especially elderly with impaired glucose homeostasis.