Lung spirometry parameters and diffusion capacity are decreased in patients with Type 2 diabetes

Aims In cohort studies, Type 2 diabetes mellitus has been associated with decreased forced 1 s expiratory volume and forced vital capacity. We examined if forced vital capacity, forced 1 s expiratory volume and diffusion lung capacity correlate with diabetes mellitus across different races in a clinical setting. Methods We examined the medical records of 19882 adults 18-97years of age in our centre from 1 January 2000 to 1 May 2009. After excluding patients with diseases causing abnormal lung function, 4164 subjects were available for analysis. We used multiple linear regressions to examine cross-sectional differences in forced vital capacity, forced 1 s expiratory volume and carbon monoxide diffusing capacity between patients with and without diabetes mellitus, after adjustment for age, age ², sex, race, height, height ², smoking, BMI and heart failure. Results Patients with diabetes (n=560) were older (62±12 vs. 55±16years), more likely to be men (56 vs. 43%), overweight (BMI 31.7±8.5 vs. 27.3±6.7kg/m ²), have heart failure (33 vs. 14%) and less likely to be Caucasians (65 vs. 76%) and never smokers (66 vs. 72%) compared with patients without diabetes (n=3604). The mean unadjusted values in patients with diabetes vs. those without were: forced vital capacity 2.78±0.91 vs. 3.19±1.03l; forced 1 s expiratory volume 2.17±0.74 vs. 2.49±0.0.83l; and carbon monoxide diffusing capacity 16.67±5.53 vs. 19.18±6.72ml ^-1min ^-1mmHg, all P<0.0001. These differences remained significant after adjustment for covariates. After race stratification, only Caucasians with diabetes had a significant decrease in all lung function measures. Conclusions Patients with diabetes have decreased lung function compared with those without diabetes. Caucasians with diabetes have more global lung function impairment compared with African-Americans and Hispanics.