Transportation noise exposure and incident type 2 diabetes: A retrospective cohort study in a large U.S. healthcare system

Objective: Transportation noise is increasingly recognized as a cardiometabolic stressor, but its relationship with type 2 diabetes mellitus (T2DM) remains poorly defined. We examined whether transportation noise exposure was associated with incident T2DM in a large, diverse U.S. healthcare system cohort. Methods: We identified adults without baseline T2DM from the Houston Methodist Learning Health System Registry (2016–2023). Transportation noise exposure was assigned at the census block group level using the 2020 U.S. Department of Transportation National Transportation Noise Map. Five noise categories were examined: Road, Rail, Aviation, Road plus Aviation and Total. Cox proportional hazards models estimated associations across predefined categories, Quiet (≤45 dB), Moderate (45–54 dB) and Loud (≥55 dB), and per 10 dB increase, adjusting for demographics, cardiometabolic risk factors, socioeconomic vulnerability and PM₂.₅. Results: Among 984 658 adults (2.1 million person-years), 39 587 developed T2DM (1.88 per 100 person-years). Loud rail noise (HR 1.14; 95% CI: 1.01–1.29) and loud total noise (HR 1.17; 95% CI: 1.03–1.33) were associated with higher T2DM risk. Continuous models showed similar patterns, with each 10 dB increase in rail noise (HR 1.09; 95% CI: 1.05–1.13) and road noise (HR 1.04; 95% CI: 1.01–1.08) associated with a higher hazard of incident T2DM. Effect sizes were modest but internally consistent and aligned with prior environmental noise studies. Conclusion: Transportation noise, particularly rail noise, was associated with higher T2DM risk. Given plausible mechanisms involving sleep disruption and stress-related neuroendocrine activation, these findings add to evidence linking environmental noise to metabolic health and motivate further studies to evaluate causality and potential benefits of noise mitigation.