Traffic Pollution Linked to Increase in Inflammation in Those Taking Insulin

People on insulin who live next to heavily trafficked roads have significantly increased levels of C-reactive protein, a marker of inflammation, compared to those living in lower-traffic areas, according to a new study published in the journal Environmental Pollution. An estimated six million people in the United States are using insulin.

Previous research on the health effects of traffic and air pollution in people with diabetes has not evaluated the role that medicines may play in relation to inflammation. To determine the association between exposure to traffic pollutants and inflammation in people taking various diabetes medicines, researchers in Massachusetts looked at 356 Puerto Rican adults with Type 2 diabetes living in the greater Boston area. Ninety-one (26%) of the participants used insulin, 197 (55%) used oral diabetes medicines, and 68 (19%) used no diabetes medicines. Roughly 20% of the subjects lived within 100 meters of one or more roads with more than 20,000 vehicles a day and another 20% lived within 100 to 200 meters of such roads. The participants’ levels of C-reactive protein were measured at the start of the study and again two years later using a high-sensitivity test.


The researchers found that C-reactive protein levels increased from 75% to 200% over the two-year study period in the 10% of participants living near the most highly trafficked areas and taking insulin compared to those in lower-traffic areas. In contrast, the 22% of people living in high-traffic areas using metformin and/or other oral diabetes medicines did not experience increases in C-reactive protein levels, suggesting that these medicines may have a protective effect against inflammation in those with Type 2.

“It’s important to know who is most vulnerable to the adverse effects of traffic pollution exposure for purposes of education and policy. People who live near busy roads and spend most of their time in these areas have been shown in many studies to have higher levels of inflammation, a risk factor for many cardiovascular and metabolic diseases. People on insulin appear to be even more susceptible to increases in inflammation when living in high traffic areas,” noted first study author Christine Rioux, PhD, MS.

“People can reduce their exposure to traffic pollution by keeping windows closed during the heaviest traffic periods of the day, using air conditioners in the summer months, and avoiding heavy exercise near busy roads, especially during peak traffic times,” she added.

Further study is needed to determine why oral diabetes medicines appear to protect against the inflammatory effects of traffic pollution, the researchers note.

For more information, read the article “Increase in inflammation linked to high traffic pollution for people on insulin” or see the study’s abstract in Environmental Pollution. And for tips on reducing inflammation, read “Put Out the Fire of Diabetes Inflammation,” by nurse David Spero.