Relationship between oxidative stress and lung function in type 2 diabetes mellitus

Abstract
Background: Diabetes mellitus causes micro and macrovascular disorder with debilitating effects on many organs including lungs. There is pulmonary impairment in type 2 diabetic patients which is usually characterized by restrictive pattern. Increased oxidative stress is associated with type 2 diabetes which may contribute to microvascular and macrovascular complications. Objectives: To assess the relationship between oxidative stress and lung function in patients with type 2 diabetes mellitus. Methods: This cross sectional study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Shahbag, Dhaka from September’2018 to August’2019. For this study, a total number of 70 male subjects were selected with the age ranging from 30-50 year by purposive sampling. Among them 35 newly diagnosed type 2 diabetic patients were included in the study group (group A). Thirty five apparently healthy subjects with similar age, sex and body mass index (BMI) constituted control group (group B). The patients were enrolled from outpatient Department of Endocrinology in BSMMU, Dhaka following selection criteria. The lung function of all subjects were assessed by portable spirometry. For evaluation of oxidative stress, plasma malondialdehyde (MDA) and catalase levels were measured. Data were expressed as mean ± SD and percentage. Statistical analysis was done by unpaired ‘t’ test, chi-square test, pearson’s correlation test and multiple regression analysis as applicable. Results: In this study, the mean percentage of predicted value of FVC, FEV1, PEFR and FEF25-75% were significantly lower (p<0.001 and p<0.05 respectively) in group A than that of group B. The mean plasma catalase was significantly lower (p<0.01) and plasma
MDA was significantly higher (p<0.001) in group A than that of group B. The frequency of restrictive pattern of pulmonary dysfunction was significantly higher in group A than that of group B (p<0.001). In addition, the PEFR was significantly positively correlated (p<0.05) with plasma catalase and FVC was significantly negatively correlated (p<0.05) with plasma MDA level in group A. Moreover, plasma catalase level was positive predictor for PEFR and plasma MDA level was negative predictor for FVC and FEV1. Conclusion: The present study reveals that restrictive pattern of pulmonary dysfunction is related to oxidative stress in type 2 diabetic patients.
Keywords
Newly diagnosed type 2 diabetic patients, FVC, FEV1, FEV1/FVC, PEFR, FEF25-75%, plasma MDA and catalase.