Introduction: Type 2 diabetes mellitus (T2DM) is associated with impaired pulmonary function. This study aimed to investigate the effect of physical activity on pulmonary function in patients with T2DM and to determine the prevalence of pulmonary function impairment in this population. Methods: A cross-sectional study was conducted on 140 patients with T2DM (70 males, 70 females; mean age 56.8 ± 7.3 years). Physical activity levels were assessed using the International Physical Activity Questionnaire (IPAQ). Pulmonary function tests, including spirometry and respiratory muscle strength measurements, were performed. Results: Physically active patients had significantly higher values of FVC (2.0 ± 0.8 L vs. 1.6 ± 0.6 L, p=0.031), FEV1 (1.7 ± 0.7 L vs. 1.3 ± 0.6 L, p=0.026), and PEF (4.0 ± 1.8 L/s vs. 3.1 ± 1.6 L/s, p=0.048) compared to inactive patients. Physical activity showed a significant positive correlation with FVC (r=0.198, p=0.019), FEV1 (r=0.209, p=0.013), and PEF (r=0.201, p=0.017). The prevalence of pulmonary function impairment was 81.4%, with 32.1% having mild restriction, 25.7% moderate restriction, and 23.6% severe restriction. Conclusion: Physical activity is significantly associated with better pulmonary function in patients with T2DM. The high prevalence of pulmonary function impairment in this population highlights the need for regular pulmonary function screening and the promotion of physical activity as a key component of T2DM management.