May 10, 2013
Air Pollution May Be Causing Insulin Resistance, Diabetes In Children
Brett Smith for redOrbit.com — Your Universe Online
While the harmful effects of air pollution on the respiratory system are well documented, a new study from a group of German researchers has found that it can increase the risk of insulin resistance, a precursor to diabetes.
The study expanded on previous research that has reached inconsistent conclusions about the link between type-2 diabetes and air pollution in adults.
"To our knowledge, this is the first prospective study that investigated the relationship of long-term traffic-related air pollution and insulin resistance in children,” said lead researcher Joachim Heinrich, an epidemiologist from the Helmholtz Center in Munich. “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."
The study of almost 400 10-year-olds, which was published in the journal Diabetologia, found that insulin resistance increased by 17 percent for every 10.6 micrograms per cubic meter increase of ambient nitrogen dioxide and by 19 percent for every 6 micrograms per cubic meter rise in particulate matter.
Heinrich said that the increased concentrations of chemicals could disrupt the body´s natural chemistry and lead to insulin resistance.
"Although 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," he said in a statement.
"Oxidative stress caused by exposure to air pollutants may therefore play a role in the development of insulin resistance,” Heinrich added. “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."
Using emission samples from road traffic, population density data, and land use information, the researchers created a model that also adjusted for several confounding factors such as socioeconomic status, cigarette smoking in the home, or low birth weight.
"There is some evidence that air pollution is associated with lower birth weight and growth restrictions–also shown previously in one of the cohorts of the present study–which are known risk factors for type 2 diabetes,” Heinrich said. “Thus, one may speculate that lower birth weight is an intermediate step or 'phenotype' between air pollution and insulin resistance. However, we found no evidence to suggest that this may be true in our cohort of children, all of whom had birth weights above 2.5kg."
The lead researcher said that the follow-up studies of this study cohort are still being conducted and his team plans to use this new information to investigate how the participants´ conditions change as they progress into adulthood.
"Moving from a polluted [neighborhood] to a clean area and vice versa would allow us to explore the persistence of the effect related to perinatal exposure and to evaluate the impact of exposure to increased air pollution concentration later in life," Heinrich said. "Whether the air pollution-related increased risk for insulin resistance in school-age has any clinical significance is an open question so far.
“However, the results of this study support the notion that the development of diabetes in adults might have its origin in early life including environmental exposures,” he concluded.