Glycemic Control and Pulmonary Function in Diabetes: A Comparative Study of Inflammatory Pathways

Abstract

Background: Diabetes mellitus (DM) is a metabolic disorder of the whole system that is becoming more and more recognized to impact the lungs through inflammation and microangiopathic mechanisms. One of the reasons for this recognition is the chronic hyperglycemia and low-grade systemic inflammation that gradually induce changes in the lungs resembling other diabetic complications in both structure and function. Objective: To compare pulmonary function between patients with controlled and uncontrolled type 2 diabetes and to investigate the association between glycemic control, systemic inflammatory markers, and lung function impairment. Methodology: This study was cross-sectional and comparative in nature to include 180 type 2 DM patients categorized into two groups by glycated hemoglobin (HbA1c): the controlled group with HbA1c levels of 7% or less and the uncontrolled one with levels above 7%. Measurements taken included fasting plasma glucose, HbA1c, high-sensitivity C-reactive protein (hs-CRP), and fibrinogen. Pulmonary function tests (PFTs), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV?), and peak expiratory flow (PEF) were conducted using a calibrated spirometer following ATS/ERS guidelines. Results: Patients with uncontrolled diabetes had significantly higher hs-CRP and fibrinogen levels (p<0.01) and lower FVC, FEV?, and PEF (p<0.001) compared to the controlled group, while FEV?/FVC remained normal, indicating a restrictive pattern. HbA1c and inflammatory markers showed a strong negative correlation with FVC and PEF (r = ?0.33 to ?0.61, p<0.001). Conclusion: Poor glycemic control and systemic inflammation are closely linked to restrictive lung impairment in type 2 diabetes. Routine spirometric evaluation should be integrated into diabetes management to detect early pulmonary involvement and prevent long-term complications.