Air Pollution Promotes Insulin Resistance

Increased particulate air pollution increases children’s risk of developing a resistance to insulin. This insulin resistance is the precursor of type 2 diabetes.

Airborne pollutants play an important role in the development of chronic diseases of the respiratory and cardiovascular systems; for diabetes, however, no reliable data has been available until now. Elisabeth Thiering and Joachim Heinrich of the Institute of Epidemiol­ogy I conducted a study on children to determine a possible association of air pollution and insulin resistance, a precursor of type 2 diabetes. They evaluated blood samples and data from 397 10-year-old children of a prospective cohort study. For all residential addresses of the children since their birth, the respective traffic-related air pollutant concentrations of particu­late matter and nitrogen dioxide (NO2) were modeled and related to insulin resistance at the age of ten years.

The socio-economic status of the families, the children’s exposure to passive smoking and their birth weight, developmental status and body mass index (BMI) were taken into account. The statistical analyses revealed that levels of insulin resistance were greater in children with higher exposure to particulate air pollution and nitrogen dioxide. Per 10.6 μg/m3 additional NO2 content in the air, the incidence of insulin resistance increased by 17 percent. Also the distance of the residence to roads with heavy traffic was significant: Near to busy roads the insulin resistance increased by seven percent per 500 meters. These relationships were independent of confounding factors such as socioeconomic status, passive smoking, or BMI.

Air pollutants are potential oxidants and can oxidize lipids and proteins directly or activate oxidizing signaling pathways. This oxidative stress may be an explanation for the development of insulin resistance due to traffic-related air pollutants. In the follow-up observation of the cohorts, the researchers are now investigating whether their observations also apply to older children and whether e.g. a change of residence with altered particulate pollution allows conclusions about the significance of exposure in early childhood and then later on. Currently, the clinical relevance of an increased risk of insulin resistance caused by particulate matter cannot be assessed. How­ever, the results support the hypothesis that the development of diabetes in adulthood is related to environmental factors earlier in life.

The insulin resistance syndrome – also known as the metabolic syndrome – refers to the common occurrence of several symptoms or diseases: obesity, elevated fasting blood glucose and blood lipid levels and high blood pressure. This so-called deadly quartet increases the risk of atherosclerosis, diabetes and heart disease.