The detrimental health effects of particulate matter exposure have been well-documented and have motivated ambitious efforts to improve air quality across the world for decades. However, countries undergoing rapid industrialisation face consequential trade-offs between economic development and the health of their populations and environments alike. Exemplifying this position is China, which faces above-average air pollution metrics in spite of aggressive efforts to improve air quality in its metropolitan centres. In a recent publication in The Lancet Regional Health ─ Western Pacific, Dr Jie Cai and colleagues explore the relationship between particulate matter 2.5 (PM2.5) exposure and the risk of comorbid type 2 diabetes and obesity, or “diabesity.” The study’s environmental and biometric analysis posits a positive association between PM2.5 exposure and the prevalence of diabesity. GlobalData epidemiologists project that the diagnosed prevalent cases of type 2 diabetes in China will increase from nearly 59,400,000 to over 63,340,000 between 2024 and 2028. By contrast, diagnosed prevalent cases of obesity are forecast to decline from over 31,430,000 to approximately 31,180,000 between 2024 and 2031. If China’s initiative to contain air pollution proves successful, these trends may lead to lower prevalent cases than originally projected.

Cai and colleagues observed the interplay between PM2.5 and diabesity by conducting a cross-sectional study in the provinces of Hubei, Yunnan, and Fujian in a cohort of 129,244 adult residents between 2018 and 2021. Health and demographic information were collected from participants via surveys and interviews, as well as anthropometric and biometric evaluation for the presentation of obesity or diabetes. To track daily PM2.5 concentration, an air pollution tracking database was utilized and cross-referenced with geospatial analysis software. Adjusting for other demographic and behavioural risk factors, the authors found a positive association between exposure to particulate matter and the burden of diabesity. Regions with higher concentrations of PM2.5 showed a higher prevalence of both obesity and diabetes. Participants exposed to PM2.5 exhibit a risk of diabesity 23% higher than those without exposure with each interquartile range increase in environmental PM2.5 concentration. Similarly, the risk of obesity and diabetes was 16% higher and 3% higher, respectively, among exposed individuals. Furthermore, different chemical constituents of PM2.5 exerted varying degrees of influence on the prevalence of diabesity. Among the five measured constituents, high concentrations of organic matter, black carbon, and sulfate (SO42-) made the largest contribution to diabesity risk. The authors suggest that these and other chemical components of PM2.5 raise the risk of obesity and diabetes by triggering inflammation and disrupting biochemical pathways associated with metabolism. However, it is proposed that unmeasured environmental and social factors, such as exposure to indoor air pollution or regional health disparities, could play confounding roles when establishing a relationship between air pollution and diabesity.

The analysis conducted by Cai and colleagues sheds light on the detrimental effects of air pollution on metabolic health. Amidst the considerable disease burden of both obesity and diabetes in China and the world, their findings present a compelling case for the further exploration of the ambient environmental contributors to metabolic dysregulation. While China’s longstanding push to reduce particulate matter appears to have reduced air pollution rates in recent years, the relationship between PM2.5 and chronic metabolic illness emphasizes the need to bolster these efforts.