The association between outdoor noise and temperature exposure with incident type 2 diabetes, and mediation by sleep and body mass index: A multi-cohort analysis

BACKGROUND: High noise exposure and temperatures may increase type 2 diabetes (T2D) risk by reducing sleep duration and increasing Body Mass Index (BMI). We studied associations between outdoor noise and nighttime temperature exposure with incident T2D in the Dutch population and assessed mediation by sleep duration and BMI.

METHODS: Six cohorts of the Geoscience and Health Cohort Consortium were linked to environmental exposures based on individuals' postal codes. Noise exposure (road, rail, air traffic) was measured as day-evening-night average decibel levels (dB). High temperature exposure was defined by days with minimum (i.e., nighttime) temperatures above 10°C during summer (June-September). We used logistic regression and sequential causal mediation models. Effect modification by sex, neighborhood socioeconomic status (nSES) and urbanization was tested. Models were adjusted for sex, age, ethnicity, educational level, follow-up time, urbanization level, nSES, and air pollution. Cohort-specific results were meta-analyzed.

RESULTS: Among 23,496 participants (mean age range 41.6 (+/-13.2) to 68.9 (+/-7.9) years), 724 developed T2D over follow-up periods ranging from 3.0 years [2.0-4.0] to 9.1 years [8.9-9.4]. Noise exposure across cohorts ranged from 53.1 [50.1-57.7] to 57.5 (+/-4.7) dB, while high nighttime temperature exposure ranged from 88 [87.0-90.0] to 106 [91.0-108.0] days. Meta-analyses showed no associations between noise (OR: 1.00, 95% CI: 0.97-1.02) or temperature exposure and incident T2D (OR: 0.99, 95% CI: 0.97-1.02). No evidence for mediation by sleep duration and BMI was observed.

CONCLUSION: Outdoor noise and elevated nighttime temperatures were not associated with incident T2D, nor mediated by sleep duration and BMI in this study.