Correlation of Pulmonary Function Tests with Anthropometry and Glycaemic Control in Type 2 Diabetes Mellitus-A Cross-sectional Study

Introduction: Diabetic patients are found to have reduced lung functions compared to their controls and their relationship with the duration of diabetes, glycaemic control, and Body Mass Index (BMI) is poorly characterised. Aim: To determine the correlation between the pulmonary function abnormalities with anthropometry, glycaemic control, and duration of diabetes in type 2 diabetic patients. Materials and Methods: A total of 80 type 2 diabetic patients were studied. BMI, Waist Circumference (WC), Waist-Hip Ratio (WHR), Fasting, postprandial blood sugar and glycosylated haemoglobin (HbA1c) were assessed from July to September 2018. Spirometry was done in accordance with the guidelines from the American Thoracic Society (ATS). Reduced pulmonary functions were defined as patients with restrictive (FEV1/FVC≥0.7 and FVC< 80% predicted) or obstructive (FEV1/FVC<0.7) impairment. Statistical analysis was done using ANOVA test and Karl Pearson Correlation coefficient. Results: The mean values of FEV1/FVC (0.8±0.08) and FVC% predicted (60.29±11.39) showed a restrictive pattern. FEF (25-75%) (r=0.241, p=0.031) and PEFR (r=0.245, p=0.029) positively correlated with duration of diabetes. BMI had a negative correlation with FVC% predicted (r=0.239, p=0.033). A negative correlation between FEV1% and Waist Circumference (WC) was observed (r=-0.232, p=0.038). HbA1c negatively correlated to FEV1/FVC (r=-0.227, p=0.043). Conclusion: Patients with type 2 Diabetes Mellitus (DM) were found to have an asymptomatic restrictive pulmonary impairment. Increased duration of diabetes, increased BMI, increased WC was associated with decreased lung functions in diabetics.