Background/Aim:
Road traffic noise affects the health of a large number of people in urbanized areas
and increases the risk of cardiovascular disease. Recent studies suggested a possible
link between exposure to noise and metabolic outcomes. However, most studies lack
information for modeling indoor noise. This study investigated the effect of outdoor
and indoor residential road traffic noise on incident diabetes mellitus (T2DM).
Methods:
We used data from 2,748 participants 45 – 75 years of age in the prospective Heinz
Nixdorf Recall study who were non-diabetic at baseline (2000 – 2003) and completed
follow-up (2005 – 2008) examinations. Road traffic noise (weighted 24-h (LDEN) and night-time (LNIGHT) means) was assessed according to the EU directive 2002/49/EC. Indoor noise exposure
for LDEN and LNIGHT was modeled considering living-room/bedroom orientation, window insulation and ventilation
behavior for different seasons. Noise annoyance was assessed with a 5-scale questionnaire.
Poisson regression with robust variance was applied to estimate relative risks (RRs)
of developing T2DM adjusting for demographic characteristics, lifestyle, body mass
index, waist circumference, air pollution (PM2.5) and noise annoyance.
Results:
In the fully adjusted model including PM2.5, a 10 dB-increase in average outdoor traffic
noise (LDEN and LNIGHT) was associated with a RR of 1.07 (95% CI, 0.93 – 1.23) for T2DM. Models for indoor
road traffic noise exposure showed very similar, but more precise point estimates
(LDEN: 1.08 (0.97 – 1.20), LNIGHT: 1.07 (0.97 – 1.20)). Models including annoyance yielded slightly lower RRs (e.g.,
1.06 (0.91 – 1.23) for outdoor LDEN).
Conclusions:
Our analyses suggest a positive association between long-term road traffic noise and
T2DM incidence. Exposure assessment might be improved by modeling indoor noise exposures.