Metabolic Control and Peripheral Airway Dysfunction in Type 2 Diabetes Mellitus: An Impulse Oscillometry-Based Analytical Study

Abstract

Background: Type 2 Diabetes Mellitus (T2DM) is increasingly recognised as a systemic disorder with extra-pancreatic organ involvement, including the lungs. Small airway dysfunction (SAD) is an early and often subclinical respiratory manifestation whose relationship with glycaemic burden remains inadequately characterised.
Objectives: To evaluate the association of glycaemic control and disease duration with small airway dysfunction in patients with T2DM using Impulse Oscillometry (IOS).
Methods: This prospective analytical study included 150 adults with confirmed T2DM attending the outpatient departments of a tertiary care hospital in South India. Clinical data including duration of diabetes, fasting blood sugar (FBS), postprandial blood sugar (PPBS), and glycated haemoglobin (HbA1c) were recorded. IOS was performed to assess airway resistance and reactance parameters, with R5-R20 and X5 serving as markers of peripheral airway dysfunction. Participants were stratified into SAD-present and SAD-absent groups; comparative, correlation, and multivariable logistic regression analyses were conducted.
Results: Small airway dysfunction was identified in 95 of 150 participants (63.3%). Compared with the SAD-absent group, patients with SAD had significantly longer diabetes duration (8.74 ± 5.81 vs. 5.21 ± 5.07 years; P = 0.0001), higher PPBS (246.91 ± 65.82 vs. 210.71 ± 63.61 mg/dL; P = 0.0005), and greater insulin use (68.4% vs. 41.8%; P = 0.003). IOS parameters differed markedly: R5-R20 (0.08 ± 0.03 vs. 0.04 ± 0.02 kPa/L/s; P = 0.0001) and X5 (-0.15 ± 0.08 vs. -0.06 ± 0.02 kPa/L/s; P = 0.0001). R5-R20 correlated positively with diabetes duration (r = 0.221, P = 0.007) and BMI (r = 0.205, P = 0.012). Multivariable regression identified diabetes duration (P = 0.001) and insulin use (P = 0.005) as independent predictors of SAD.

Conclusion: Peripheral airway dysfunction in T2DM is significantly associated with disease chronicity and treatment intensity. IOS serves as a sensitive tool for detecting early metabolic-pulmonary interactions even in the absence of overt respiratory symptoms, and may inform targeted screening strategies in routine diabetes care.