Exposure to air pollution, a new study finds, may increase glucose intolerance, a precursor of diabetes.
German researchers found the effect particularly strong in people who are already considered prediabetic because of abnormally high blood sugar levels.
The study, in Diabetes, used data on 2,944 people in and around Augsburg, Germany, tracking their glucose levels and other metabolic measures along with levels of air pollutants — particulate matter and nitrogen dioxide — where they lived.
They found that over the entire population, for each 7.9 microgram per cubic meter increase in soot and other particulate matter, there was a 15 percent higher rate of insulin resistance, a marker of Type 2 diabetes. (On smoggy days, levels of particulate matter typically exceed 50 micrograms per cubic meter.) For prediabetics the risk increased by almost 46 percent for each unit increase in air pollution. The researchers controlled for sex, smoking, body mass index, socioeconomic status and many other variables.
The underlying mechanism is not well understood and the findings are correlational and do not prove cause and effect, but the authors suggest that air pollution may lead to insulin resistance by increasing body-wide inflammation and levels of oxidative stress.
“For people who already have bad metabolism, adding air pollution makes them respond more strongly,” said the senior author, Annette Peters, an adjunct professor at the Harvard T. H. Chan School of Public Health. “This means they really need a healthy lifestyle. The effect of air pollution can be countered with healthy diet and exercise.”