ABSTRACT:
Introduction Ozone (O3) is one of the leading and growing air pollutants in China, and was proved to be related to insulin resistance. As the prevalence of diabetes continues to surge, we aimed to examine the association between long-term warm-season O3 exposure and incident hyperglycemia across different baseline in glycemic status. Methods We included participants from the ChinaHEART project who were at high cardiovascular disease risk and free of diabetes (N=501,560; 57.5% female). Ambient O3 concentration data were obtained from the Tracking Air Pollution in China, with long-term exposure defined as the 3-year average warm-season (May to October). The primary outcomes were incident diabetes and incident prediabetes during a two-year follow-up period. A Cox proportional hazard model was performed to estimate associated risk. Results The mean 3-year warm-season O3 concentration was 103.2 ug/m3. During follow-up, 16,355 incident diabetes cases and 107,508 incident prediabetes cases were identified among normoglycemic participants at baseline. Each 10.0 µg/m³ increment in 3-year O3 exposure was associated with a 33% increased risk of prediabetes and a 23% increased risk of diabetes. Compared with the lowest tertile of O3, the highest tertile was associated with significantly increased risks of incident diabetes and incident prediabetes.In the meantime, among the 283,622 participants with prediabetes at baseline, 42,295 developed diabetes during follow-up. The multivariable-adjusted HR for diabetes per 10.0 µg/m³ increment in three-year O3 exposure was 1.35, with the HR for the highest tertile being 2.62. Conclusions This study identifies long-term warm-season O3 exposure as an independent risk factor for glycemic deterioration. Strengthening warm-season O3 control should be prioritized as an integral component of strategies aimed at halting diabetes progression at its earliest reversible stages.