The Sound of Diabetes

An interesting article come out recently about how long-term exposure to road traffic noise can increase your risk of  diabetes.  The study used data collected in the population-based Danish Diet, Cancer and Health cohort using 57,053 participants between the ages of 50-64 and followed these people for 9.6 to calculate the amount of traffic noise they were exposed to. It was impressive how much data this study had collected, due to all subject living in Denmark the researchers had access to their medical records plus questionnaires the subjects filled out about diet, lifestyle habits, present or previous smoking, physical activity level, health status, and social factors. Subjects were determined to have diabetes if they had five blood glucose measurements within 1 year, or two blood glucose measurements per year for 5 consecutive years; or > 1 purchase of insulin or oral glucose-lowering drugs within 6 months registered in the Register of Medicinal Product Statistics (n=3869).  The researchers decided to further refine their sample by including people who had confirmed diabetes based on just their blood glucose levels (n=2752) and run there test on both groups. 

To determine the amount of traffic noise the subjects were exposed to a complicated model calculated by SoundPlan. This software used multiple variables such as point for noise estimation, road links with information on annual average daily traffic, vehicle distribution, travel speed, and road type, polygons for all buildings etc to determine the amount and level of noise the subject was exposed to. Three models were then ran with this data, model 1 was adjusted to the sample's age, model 2 adjusted for age, sex, lifestyle confounders, socioeconomic confounders, calendar year, railway and airport noise, model 3 was the same as model 2 plus the addition of residential exposure to NOx gases.  The study found that a 10-dB higher level of exposure to road traffic noise at during a 5 year period was associated with statistically significant 8% (95% CI: 1.02, 1.14 all diabetes) and 11% (95% CI: 1.05, 1.18 confirmed diabetes) higher risk of incident diabetes, respectively, based on model 3 adjustment. However they found that railway noise (noise ≥ 60 dB) did not seem to be associated with either the confirmed or all diabetes groups.

While this article was interesting I believe it should be taken with a grain of salt and perhaps wait for more research to be conducted. The article had many variables to work with and any one of them could have been miscalculated considering we are dealing with noise level which can fluctuate greatly. The data presented here is only as good as the model used and considering this experiment was not done under a controlled laboratory setting there is a lot of room for error. The experimenters also did not select which type of diabetes the subjects had. The assumption was that due to the older age of the subject and that type II diabetes is more prevalent, the subjects most likely had type II diabetes which is not necessarily the cause. To say that traffic noise effects all types of diabetes is probably not the case and further research should be done on how it affects each type.

Thomas Becker, Anne Tjonneland, and Kim Overvad. "Long-Term Exposure to Road Traffic Noise and Incident Diabetes: A Cohort Study." Environ Health Perspect 2nd ser. 121 (2013): 217-22. PMC. 10 Dec. 2012. Web. 1 May 2013. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3569689/>