Background: At present, chronic respiratory diseases are a major burden in terms of morbidity and mortality and are of increasing public health concern in China. Meanwhile, the prevalence of diabetes has increased by more than 10 times over the last 40 years. While a few studies have investigated the association between chronic respiratory diseases and diabetes mellitus, the association is not clear. This study aimed to explore this association and provide evidence. Methods: In this single-center study, we enrolled participants aged >= 20 years undergoing at least two regular health check-ups from 2009 to 2019 at MJ Healthcare Center in Beijing. Each health check-up included physical examination, biochemical tests, a pulmonary function test, a questionnaire. A total of 11,107 adults were included, and cross-sectional and longitudinal analyses were performed. Results: We found that both prediabetic and diabetic adults had lower lung function than the normal population at baseline, indicating that lung function decline may start from prediabetic status. Quantitatively, with 1-mmol/L increase in fasting plasma glucose level, the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FVC% and FEV1 % lowered by 25 ml, 13 ml, 0.71-1.03%, and 0.46-0.72%, respectively. However, no significant difference was found in the rates for the lung function decline among different baseline diabetes statuses. Conclusion: People with higher blood glucose level had more severe lung function decline, with decline starting from prediabetic status, but no significant difference was noted in the rate of lung function decline based on different baseline diabetic statuses.