New research shows that growing up in areas where air pollution is increased raises the risk of insulin resistance (the precursor to type ii diabetes) in children.
Previous studies have identified links between air pollution and other chronic conditions such as cardiovascular and respiratory disease. However to date, epidemiological studies that have examined associations between long-term exposure to traffic-related air pollution and type ii diabetes in adults have been inconsistent, and studies on insulin resistance in children are sparse. Thus this new study sought to explore the possible association between air pollution and insulin resistance in children.
Even though toxicity differs between air pollutants, they are all considered potent oxidisers that act either directly on lipids and proteins or indirectly through the activation of intracellular oxidant pathways. Oxidative stress caused by exposure to air pollutants may therefore play a role in the development of insulin resistance. In addition, some studies have reported that short-term and long-term increases in particulate matter and nitrogen dioxide (NO2) exposure lead to elevated inflammatory biomarkers, another potential mechanism for insulin resistance.
In this new study, fasting blood samples were collected from 397 10-year-old children as part of a larger birth cohort study. Individual-level exposures to traffic-related air pollutants at birth address were estimated by analysing emission from road traffic in the neighbourhood, population density and land use in the area, and the association between air pollution and insulin resistance was calculated using a model adjusted for several possible confounders including socioeconomic status of the family, birth-weight, pubertal status and BMI. Models were also further adjusted for second-hand smoke exposure at home.
The researchers found that in all crude and adjusted models, levels of insulin resistance were greater in children with higher exposure to air pollution. Insulin resistance increased by 17% for every 10.6 µg/m3 (2 standard deviations from the mean) increase in ambient nitrogen dioxide (NO2) and 19% for every 6 µg/m3 (2 SDs) increase in particulate matter of up to 10 μm in diameter. Proximity to the nearest major road increased insulin resistance by 7% per 500 metres. All the findings were statistically significant.
Insulin resistance levels tended to increase with increasing air pollution exposure, and this observation remained robust after adjustment for several confounding factors, including socioeconomic status, BMI and passive smoking.
Reference:
E. Thiering & J. Cyrys & J. Kratzsch & C. Meisinger & B. Hoffmann & D. Berdel & A. von Berg & S. Koletzko & C.-P. Bauer & J. Heinrich. Long-term exposure to traffic-related air pollution and insulin resistance in children: results from the GINIplus and LISAplus birth cohorts. Diabetologia. DOI 10.1007/s00125-013-2925-x
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