Background/Aim: We investigated the effects of chronic exposures to particulate and traffic-related air pollution on allostatic load (AL), a marker of cumulative biological risk, among youth with type 1 diabetes. Methods: Participants were drawn from five clinical sites of the SEARCH for Diabetes in Youth study (n=2,338). Baseline questionnaires, anthropometric measures, and a fasting blood test were taken at a clinic visit between 2001 and 2005. AL was calculated using 10 biomarkers reflecting cardiovascular, metabolic, and inflammatory risk. Monthly and annual residential exposures to particulate matter < 2.5 µm in diameter (PM2.5) and proximity to heavily-trafficked major roadways were estimated for each participant. Separate linear mixed models adjusted for sociodemographic and lifestyle factors were conducted for each exposure. Results: No significant associations were observed between exposures to PM2.5 or proximity to traffic and AL in our main analysis. However, several associations were identified in stratified analyses. Among non-white participants, an interquartile range (IQR) increase in monthly average PM2.5 was inversely associated with AL (β=-0.18, 95% CI: -0.36, -0.01), while residing in proximity to heavily-trafficked major roadways was positively associated with AL (β=0.73, 95% CI: 0.19, 1.3) and the cardiovascular and inflammatory AL subscales. Among non-Hispanic white participants and female participants, an IQR increase in monthly average PM2.5 was positively associated with the inflammatory AL subscale (β=0.10, 95% CI: 0.03, 0.18 and β=0.11, 95% CI: 0.02, 0.20, respectively). Conclusions: Among youth with type 1 diabetes, the effects of chronic exposures to particulate and traffic-related air pollution on AL and its subscales may differ by race/ethnicity and sex.