Assessment of the Effects of Cigarette Smoking on Lung Functions and Glucose Metabolism in Asymptomatic Current Cigarettes Smokers

Abstract

Background: tobacco smoking has been considered a risk factor for obstructive airway diseases, insulin resistance and development of type 2 diabetes mellitus (DM).Aim: to assess the effects of cigarette smoking on lung functions and glucose metabolism in asymptomatic current cigarettes smokers.Methodology: this case-control study was conducted on 100 asymptomatic current cigarette smokers and 100 age and sex matched lifelong non-smokers. Data regarding age, sex, smoking history including age of starting, smoking index and smoking duration were recorded. Spirometric-indices (VC %, FVC%,, FEV1 %,FEV1/FVC ratio, FEF25-75%), serum fasting plasma glucose mg/dl (FPG) and glycated hemoglobin % (HbA1C%) were measured.Results: obstructive ventilatory defect and small airways obstruction were significantly higher in asymptomatic smokers than non-smokers (21% vs. 7% and 42% vs. 10% respectively) (p 0.004 and 0.001 respectively). Among smokers the frequencies of the pre-DM and DM detected by FPG there were higher than non-smokers (41% vs. 9% and 10% vs. 1% respectively). Moreover, there was higher frequencies of pre-DM and DM detected by HbA1C among smokers compared to non-smokers (60% vs. 11% and 10% vs. 1% respectively) (p 0.001). In smokers group both FEV1/FVC and FEF25-75% was positively correlated with age of starting smoking /yrs (p 0.001), and negatively correlated with smoking index, smoking duration, FPG and HbA1C (p 0.001). The HbA1C was positively correlated with smoking index and smoking duration and negatively correlated with age of starting smoking/yrs (p˂ 0.05). Smokers have 17.1 more risk of developing DM, 3.5 more risk of developing obstructive ventilatory defects and 6.5 more risk of developing small airways obstruction compared to non-smokers. Conclusion:smoking is a risk factor for development of DM, obstructive ventilatory defect and small airways obstruction. Both reduced ventilatory functions and increased FPG and HbA1C negatively affected each other's.