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February 24, 2016

Air Pollution Has Similar Adverse Effects as Obesity on Risk for Type 2 Diabetes

USC Environmental Health
Air Pollution Adversely Effects Insulin Sensitivity

PRESS: Reuters, Endocrine Today, Everyday Diabetes, Newsmax, Environment Today

It is a well-established fact that obese people are more likely to develop diseases such as diabetes, heart disease and be at increased risk for stroke. In a recent study published in Diabetes Care journal, USC researchers in the USC Keck School of Medicine found that fine particulate matter  that mostly comes from vehicles exhaust in Los Angeles has a similar significant effect as obesity on the risk of type 2 diabetes. “The most important clinical meaning of our results is that the impact of PM2.5 on Type 2 Diabetes related traits was comparable to the influence of obesity on these traits,” said the study’s lead author, postdoctoral research associate Zhanghua Chen.

With years of studying the role that air pollution plays in health outcomes, researchers at the Southern California Environmental Health Sciences Center (SCEHSC) have equipped themselves to study how air pollution affects an individual’s risk for acquiring type 2 diabetes at some point in their lifetime.

In a study with Mexican American adults, who are at high risk of type 2 diabetes, Dr. Frank D. Gilliland, director of the SCEHSC, Chen and colleagues in the Keck School of Medicine at USC looked at how exposures to specific air pollutants and heavy traffic near their homes during various time periods from several days to a year impacted the risk of type 2 diabetes among this high risk group of Mexican-Americans.

The research team found that participants exposed to higher short-term average PM2.5 concentrations were more insulin resistant, had lower HDL to LDL (good to bad cholesterol) ratios and higher fasting glucose and insulin. Higher annual average exposure to PM2.5 also adversely affect fasting glucose, insulin resistance and blood lipids.  Additionally, obese people are more susceptible to the negative effects of short-term PM2.5 on insulin sensitivity.

“The uniqueness of this study paired air pollution measures with detailed and more direct measurements of insulin sensitivity and beta-cell function using a frequently sampled intravenous glucose tolerance test,” said Chen. “The Mexican American population is known for their high risk for obesity and, but they were less studied for the relationship between air pollution and type 2 diabetes.”

“Our significant findings about the detrimental impact of air pollution exposures on increased risk of type 2 diabetes indicate that stricter control of air pollution is needed to early prevent type 2 diabetes. Results from this study can provide policy makers with the information needed to formulate policy and regulation to protect public health,” said Chen.

Zhanghua Chen, Muhammad T. Salam, Claudia Toledo-Corral, Richard M. Watanabe, Anny H. Xiang, Thomas A. Buchanan, Rima Habre, Theresa M. Bastain, Fred Lurmann, John P. Wilson, Enrique Trigo, and Frank D. Gilliland. Ambient Air Pollutants Have Adverse Effects on Insulin and Glucose Homeostasis in Mexican Americans, Diabetes Care published ahead of print February 11, 2016, doi:10.2337/dc15-1795

Funding. This work was supported by National Institutes of Health grants DK-061628, M01-RR-0043, and UL1-TR000130, American Diabetes Association Research Award Clinical Research grant 7-09-CT-09, the Southern California Environmental Health Sciences Center funded by the National Institute of Environmental Health Sciences (grant 5P30ES007048), National Institute of Environmental Health Sciences grant 5P01ES011627, and the Hastings Foundation.

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