What environmental factors affect the risk of type 2 diabetes?

New research studies the association between environmental quality in more than 3,000 counties across the United States and finds intriguing differences between rural and urban areas.

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New research suggests that several environmental factors affect the risk of type 2 diabetes.

Estimates indicate that more than 30 million In the United States, people are currently living with type 2 diabetes and 84 million more are living with prediabetes.

Diabetes complications are the leading cause of blindness, kidney failure and amputation in adults.

Type 2 diabetes has seen a rapid increase in recent years. Between 2002 and 2012, the condition increased by 4.8% each year in the United States

Added to a genetic predisposition, diet and insufficient physical activity largely explain this increase. But are these two risk factors the only environmental influences behind the rising trend in diabetes in the United States?

New research has attempted to examine whether environmental factors in rural and urban areas also play a role. Dr. Jyotsna Jagai, assistant research professor of environmental and occupational health sciences at the University of Illinois at Chicago (UIC) School of Public Health, is the first author of the new study.

Dr. Jagai and the team examined people in 3,134 counties across the United States and published their findings in the Diabetes Survey Journal.

The researchers wanted to measure the cumulative environmental effects on the risk of developing type 2 diabetes. To this end, they developed an environmental quality index (EQI), which included data on air quality , water and soil, as well as socio-demographic factors in a given area.

Sociodemographic factors included average household income, education level, violent crime rates or property crime rates.

The EQI also included so-called constructed domain factors. That is, how many fast food restaurants were in an area, how many fatal accidents occurred, and how many highways, roads, or public housing there were.

Dr. Robert Sargis, study co-author and UIC Associate Professor of Endocrinology, Diabetes and Metabolism at the College of Medicine, explains the scientific value of using the EQI.

He says: “The cumulative assessment of the EQI is unique […] In most studies, we don’t look at the combination of factors. We look at unique chemicals or unique classes of chemicals and how they are associated with disease risk.

“This study pulls together all of the factors that we believe increase risk and aggregates them into a single measure to look at the cumulative environment.”

The results of this analysis showed that overall, poorer environmental quality was associated with a higher prevalence of type 2 diabetes.

Research has linked lower air quality and built and socio-demographic factors with a higher risk of diabetes in rural areas. However, in urban areas, researchers only associated atmospheric and sociodemographic factors with diabetes risk.

“There may be something happening in rural areas that is different from what is happening in urban areas. Our results suggest that environmental exposures may be a more important factor in rural counties than in urban areas in the United States,” says Dr. Jagai.

The authors mention that the results confirm previous studies that found an increased risk of diabetes in urban areas with poor air quality, or studies that showed that changes in air quality could increase insulin resistance. But, say the researchers, the influence of the environment is much more than pollution.

The environment we are exposed to goes beyond just pollutants. Our health depends on these combined effects, such as socio-demographic or constructed stressors, which can impact our livelihoods.

Dr. Jyotsna Jagai

“Understanding local social and economic demographic factors can help communities develop environmental regulations and policies to improve health outcomes for their residents,” adds the lead author.