Higher CO2 and heatwave exposure associated with diabetes in Chinese baseline cohort analysis

A spatial epidemiological study published in BMC Medicine examined CO2 and heatwave exposure in relation to diabetes, prediabetes and fasting blood glucose using baseline data from 134,403 participants in a multicenter Chinese cohort. Researchers estimated CO2 exposure at 10-km resolution and heatwave exposure at 27-km resolution, applying multilevel regression models adjusted for individual covariates and accounting for community-level clustering.

Higher CO2 concentrations were associated with higher odds of diabetes (OR 1.14, 95% CI 1.09–1.19), as was increased heatwave frequency (OR 1.48, 95% CI 1.17–1.89). Both exposures were also associated with higher fasting blood glucose. The supplied text does not specify the exposure increments underlying these estimates, limiting interpretation of their magnitude. CO2 associations were stronger among participants with less education, rural residence and non-compact built environments.

Among participants who experienced heatwaves, mediation analysis estimated that BMI accounted for 8.2% of the CO2–diabetes association and 2.9% of the CO2–prediabetes association. These findings suggest environmental correlates of diabetes burden, but the baseline observational design cannot establish temporality or causation. Spatial exposure estimates also do not directly measure personal exposure, and mediation estimates should not be interpreted as proof of a biological pathway.