Objective To investigate the impact of long-term ozone (O₃) exposure on diabetes incidence and the associated excess risk among middle-aged and elderly adults in China.

Methods Based on the cohort data from the China Health and Retirement Longitudinal Study (2011-2020), combined with environmental variables including O₃ mass concentrations from the China high-resolution and high-quality near-surface air pollutant dataset, a Cox proportional hazards model with time-varying exposures was applied to estimate the hazard ratio (HR) for diabetes incidence associated with increased O₃ mass concentrations.The excess risk was estimated to quantify the disease burden.

Results A total of 1 993 new diabetes cases were recorded during the follow-up period, with a cumulative incidence of 12.48%.Long-term O₃ exposure was significantly associated with an increased risk of diabetes.In the fully adjusted model, each 10 μg/m³ increase in O₃ concentration was associated with an 8.7% rise in diabetes risk (HR=1.087, 95% confidence interval: 1.036-1.139).Substantial regional variations in O₃ exposure were observed, with provinces and cities such as Shandong, Shanghai and Jiangsu exhibiting average population weighted concentrations exceeding 100 μg/m³.Model estimates indicated that O₃ exposure contributed to 362 excess diabetes cases in the study population over the decade, accounting for an attributable risk of 18.16%.

Conclusion Long-term O₃ exposure can significantly increase the risk of diabetes in middle-aged and older adults.It is recommended to incorporate O₃ as a key target in environmental governance for diabetes prevention and control and to continue the improvement of air quality to reduce the burden of O₃-related chronic diseases.