Association between transportation noise exposure and type 2 diabetes risk in a French prospective cohort: the E3N-generations cohort

Background It has been suggested that exposure to transportation noise is associated with an increased risk of type 2 diabetes (T2D), but only a few prospective cohort studies have investigated this hypothesis for railway and aircraft noise. In the BROUHAHA study, we examined this association using data from the E3N-Generations cohort of French women. Methods We included 18,926 women residing in the Île-de-France or Auvergne-Rhône-Alpes regions (France) between 2000 and 2014. Annual average L_den (day-evening-night level) and L_n (night level) values were estimated for road traffic, railway, and aircraft noise using strategic noise maps. Incident T2D cases were identified through follow-up questionnaires and validated using drug reimbursement insurance databases. Cox proportional hazards models were used to calculate adjusted hazard ratios (HRs) and 95 % confidence intervals (CI). Results A 10 dB(A) increase in road traffic noise exposure was associated with a moderate increase in T2D risk (L_den: HR = 1.08, 95 %CI: 1.00, 1.18; L_n: HR = 1.12, 95 %CI: 1.01, 1.25). Adjustment for NO₂ and PM_2.5 slightly increased the estimated HRs. No association was observed between railway or aircraft noise and T2D incidence. Conclusion In this prospective cohort study of French women, exposure to road traffic noise was associated with a moderate increase in T2D risk, independently of NO₂ and PM_2.5 exposure. This association was slightly stronger for night-time noise exposure than for day-evening-night exposure.