Prevalence, Patterns, and Clinical Factors Associated With Pulmonary Complications in Patients with Diabetes Mellitus: A Cross-Sectional Study

Abstract

Background: Diabetes mellitus is a chronic metabolic disorder with well-established microvascular and macrovascular complications. Emerging evidence indicates that the respiratory system may also be affected; however, pulmonary involvement in diabetes often remains subclinical and under-recognised.

Objective: To determine the prevalence, pattern, and associated factors of pulmonary function impairment among patients with type 2 diabetes mellitus.

Methods: An analytical cross-sectional study was conducted among adult patients with type 2 diabetes mellitus and age- and sex-matched non-diabetic controls. Clinical data including duration of diabetes, smoking status, and glycaemic control (HbA1c) were recorded. Pulmonary function was assessed using standardised spirometry following American Thoracic Society/European Respiratory Society guidelines. Spirometric patterns were categorised as normal, obstructive, restrictive, or mixed. Statistical analyses were performed to identify factors associated with pulmonary function impairment.

Results: Pulmonary function impairment was observed in 42.0% of patients with diabetes. Restrictive ventilatory defect was the most common abnormality (25.3%), followed by obstructive (11.3%) and mixed patterns (5.4%). Mean FEV₁, FVC, and FEV₁/FVC ratio were significantly lower in patients with diabetes compared with controls (p < 0.001). Poor glycaemic control, longer duration of diabetes, and smoking history were independently associated with abnormal spirometry. A significant inverse correlation was observed between HbA1c levels and FEV₁ (% predicted).

Conclusion: Pulmonary function impairment is common among patients with type 2 diabetes mellitus and is associated with poor glycaemic control and longer disease duration. Early identification of pulmonary involvement may improve comprehensive risk assessment in diabetes care.