Abstract
Background: Diabetes mellitus (DM) is a lifestyle disorder associated with long-term damage to various organs. Abnormal respiratory functions have found to be associated with diabetes, yet the significance of this association is not convincingly proven.

Aims and Objectives: The concept of undertaking this project is to know the extent of damage done to the respiratory system by DM and its relation with the duration of diabetes.

Materials and Methods: In our study, 70 non-smoker type 2 DM patients attending the medicine outpatient department in our hospital were selected. Approval of the Institutional Ethical Committee was taken before commencement of the study. Same number of normal healthy subjects was taken as the control group. The patients are divided into three groups by the duration of diabetes. Spirometry was performed using an electronic spirometer and various lung volumes and capacities were recorded.

Results: P value was highly significant for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, and peak expiratory flow rate (PEFR) between the cases and the controls (i.e., <0.05). P value was highly significant for FVC, FEV1, slow vital capacity, and PEFR between <5 years and 5–10 years duration of diabetes (i.e., <0.05), showing that these pulmonary functions were reduced significance.

Conclusion: Type 2 DM affects the lungs and the changes are more in favor of restrictive lung disease and there is relation with the duration of diabetes as well.

Key words: Type 2 Diabetes Mellitus; Pulmonary Functions; Spirometry; Restrictive Lung Disease; Obstructive Lung Disease