Pulmonary function test abnormalities in type 2 diabetes mellitus: A cross-sectional study from a tertiary care center in northern India

Background: Type 2 diabetes mellitus (T2DM) affects multiple organ systems, including the eyes, nerves, kidneys, and cardiovascular system. However, its impact on pulmonary function remains underexplored. This study evaluated pulmonary function test (PFT) abnormalities in patients with T2DM and compared them with non-diabetic controls. Methods: A descriptive cross-sectional study was conducted on 62 subjects—31 patients with T2DM and 31 age- and sex-matched non-diabetic controls. Pulmonary function was assessed using spirometry, measuring forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), peak expiratory flow rate (PEFR), FEV₁/FVC ratio, and forced expiratory flow (FEF 25–75%). Data were analyzed using Student’s unpaired t-test and correlation analysis. Results: Diabetic patients showed significantly lower mean values of FVC, FEV₁, FEV₁/FVC ratio, PEFR, and FEF 25–75% compared with controls (p<0.01). Correlation analysis revealed a negative association of fasting blood sugar (FBS), postprandial blood sugar (PPBS), and HbA1c with all pulmonary function parameters. Among diabetic patients, 11 (35%) had normal pulmonary function, 8 (26%) exhibited an obstructive pattern, and 12 (39%) demonstrated a restrictive pattern, with restrictive involvement being the most prevalent. Conclusion: Patients with T2DM exhibit significant impairment in pulmonary function compared to non-diabetic individuals, with restrictive lung involvement being more common than obstructive changes. Poor glycemic control is associated with greater pulmonary dysfunction, highlighting the need to consider the lungs as a target organ in diabetes management.