Lung: Another Victim of the Silent killer Diabetes- A Cross-sectional Study

Abstract

Introduction: Diabetes is a multisystem disorder with well known complications involving various organs in the body. The presence of abundant connective tissue and microvasculature raises the possibility that lung may also be affected in diabetes. Aim: To evaluate the pulmonary function parameters in patients with diabetes mellitus and to determine their correlation with glycaemic control, duration of diabetes and other microvascular complications. Materials and Methods: This is a cross-sectional study done between September 2018 and March 2019. A total of 300 type 2 diabetic patients, aged 30-70 years, with duration of diabetes more than 1 year, were included in the study. Thorough history was taken regarding the duration of diabetes and symptoms of the complications. All of them were evaluated for diabetic microangiopathies: nephropathy (by 24 hour urinary protein excretion), retinopathy (by direct ophthalmoscopy) and neuropathy (by clinical examination). Glycosylated Haemoglobin (HbA1c) was measured as an indicator of glycaemic control. Spirometry and single breath diffusion capacity for carbon monoxide were performed on all the subjects. Pulmonary Function Test (PFT) parameters of each subject were compared with the normal values. Unpaired t-test and one-way analysis of variance (ANOVA) were used. Correlation and regression studies were used to find out the strength of association between Diffusing Capacity of the Lungs for Carbon Monoxide (DLCO) and the following: the duration of disease, HbA1c and presence of other microvascular complications. Results: Pulmonary function parameters like Forced Expiratory Volume in first second (FEV1), Forced Vital Capacity (FVC), Peak Expiratory Forced Rate (PEFR) and DLCO were below the normal values in 53% of diabetic patients included in the study. Majority of them had a restrictive ventilation pattern. The diffusion capacity corrected for Alveolar Volume (VA) as measured by DLCO/VA was significantly reduced in those with longer duration of diabetes and in those with other microvascular complications. However, the poor lung functions had no correlation with the HbA1C values. Conclusion: This study demonstrated that lungs are indeed affected in patients with type 2 diabetes. The presence of extrapulmonary microangiopathy and duration of the disease may predict the incidence and the severity of the lung function abnormality.