Even among counties falling within EPA limits for exposure, those with highest versus the lowest levels of PM2.5 pollution had a more than 20 percent increase in diabetes prevalence, which remained after controlling for diabetes risk factors.

"From a policy perspective, the findings suggest that the current EPA limits on exposure may not be adequate to prevent negative public health outcomes from particulate matter exposure," Brownstein says.

"Many environmental factors may contribute to the epidemic of diabetes in the United States and worldwide," notes Allison Goldfine, MD, head of clinical research at the Joslin Diabetes Center and a coauthor on the study. "While a lot of attention has correctly been attributed to caloric excess and sedentary behaviors, additional factors may provide novel approaches to diabetes prevention."

Based on their findings, the researchers call for more study of environmental factors in diabetes, including basic research on the inflammatory mechanisms in diabetes and the role of PM2.5.

"We would like to access better individual-level data on diabetes and exposure," adds Brownstein. "We also have an interest in investigating this finding internationally where standards may be less stringent."

Source: Children's Hospital Boston