Long-term noise exposure and the risk for type 2 diabetes: a meta-analysis.

Diabetes mellitus is one of the leading causes for disability and mortality in modern societies. Apart from personal factors its incidence might be influenced by environmental risks such as air pollution and noise. This paper reports a systematic review and meta-analysis on the risk for type 2 diabetes due to long-term noise exposure. Electronic searches in MEDLINE, EMBASE and the Internet yielded 9 relevant studies (5 for residential and 4 for occupational exposure). They were checked against a predefined list of safeguards against bias producing individual quality scores, which were then fed to MetaXL to conduct a quality effects meta-analysis. People exposed at their homes to roughly L(den) > 60 dB had 22% higher risk (95% confidence interval [CI]: 1.09-1.37) for type 2 diabetes in comparison to those exposed to L(den) < 64 dB; when studies reporting contentious exposure categories were excluded, there was still 19% risk (95% CI: 1.05-1.35) for L(den) = 60-70 dB versus L(den) < 60 dB. In occupational environment there was not significant risk (relative risk [RR] = 0.91, 95% CI: 0.78-1.06) for < 85 dB versus >85 dB. There was no heterogeneity in the two groups (I² = 0.00). The results should be interpreted with caution due to methodological discrepancies across the studies; however, they are indicative of the close links that noise pollution might have not only to cardiovascular diseases but to endocrine dysfunction as well.