Association Between Long-Term Exposure to Particulate Matter and Glycated Hemoglobin Levels: A Cohort Study from the Korean Genome and Epidemiology Study

Background: Ambient air pollution, particularly particulate matter (PM), has been linked to metabolic disorders, including diabetes. We evaluated associations between long-term exposure to coarse particulate matter (PM10) and fine particulate matter (PM2.5) and glycated hemoglobin (HbA1c) levels in a Korean population and assessed whether specific subgroups exhibited heightened susceptibility. Methods: We analyzed 6940 participants without diabetes from the Korean Genome and Epidemiology Study (KoGES) Ansan-Ansung cohort. Participants contributed 35,395 observations across a mean follow-up of 5.1 visits (2005–2017). Linear mixed models estimated associations between PM exposure and HbA1c while adjusting for covariates, including body mass index (BMI), time, and region. Subgroup analyses stratified by sex, age, BMI, region, education, smoking status, drinking status, and exercise. Results: Higher long-term PM10 exposure was associated with elevated HbA1c (β = 0.0347 per interquartile range [IQR] increase of 9.48 μg/m3; 95% CI: 0.0220, 0.0473; p < 0.001). PM2.5 showed a comparable positive association (β = 0.0166 per IQR of 8.67 μg/m3; 95% CI: 0.0010, 0.0321; p = 0.037). Associations were stronger among older adults (≥60 years: β = 0.0789 vs.