Long-term exposure to fine particulate matter and diabetes in Bangladeshi adults: Can clean air targets curb the rising diabetes burden?

Background: Diabetes is a growing public health challenge in Bangladesh, potentially exacerbated by high levels of air pollution. However, no nationally representative epidemiological evidence exists in Bangladesh. We therefore investigated the association between long-term exposure to PM_2.5 and diabetes and estimated the potential health benefits of achieving national and international clean air targets. Methods: This retrospective study included 13,965 adults (8284 women and 6965 men) who participated in the nationally representative Bangladesh Demographic and Health Survey (BDHS) 2022. The annual average concentrations of PM_2.5 were derived from high-resolution, calibrated satellite data matched to their residential addresses. Diabetes was identified as fasting plasma glucose ≥7.0 mmol/L and/or self-reported use of glucose-lowering medication. Generalized Estimating Equation models were used to estimate the associations between PM_2.5 and diabetes, and a Generalized Additive Model was employed to characterize the exposure-response relationship. We also evaluated potential Effect Measure Modification across various sociodemographic groups. The diabetes burden attributable to PM_2.5 and the potential health benefits of achieving national and World Health Organization (WHO) clean air targets were estimated using the attributable fraction. Results: Each 10 μg/m³ increase in 3-year average PM_2.5 concentration (with a 1-year lag) was associated with a 10 % higher risk of diabetes (adjusted Risk Ratio: 1.10; 95 % CI: 1.04, 1.17), with a stronger effect observed among individuals with obesity. Achieving national and WHO air quality targets could potentially reduce the population-level prevalence of diabetes by 4.6 % to 7.5 %. Greater benefits were seen among women, older adults, individuals with obesity or hypertension, and urban populations. Conclusion: Our results demonstrate that long-term exposure to PM_2.5 was associated with increased prevalence of diabetes in Bangladeshi adults. Achieving clean air targets can substantially reduce the national and regional population-level burden of diabetes, underscoring the significant health benefits of reducing air pollution.