Estimates indicate that over 30 million people in the United States are currently living with type 2 diabetes, and another 84 million are living with prediabetes. Complications from diabetes are the leading cause of adult blindness, kidney failure, and amputations. Type 2 diabetes has witnessed a rapid increase in the last few years. Between 2002 and 2012, the condition increased by 4.8% each year in the U.S. When added to a genetic predisposition, diet and insufficient physical activity account for a lot of this increase. But, are these two risk factors the only environmental influences that explain the rising trend of diabetes in the U.S.? Although in rare cases isolated exposure to a single chemical is sufficient to drive diabetes developmet, it is much more likely that multiple exposures, coupled with additional risk factors, are required to drive diabetes pathogenesis. Studies have shown that various pollutants can disrupt glucose homeostasis and promote metabolic dysfunction (e.g. plasticizers and flame retardants). These diabetogenic agents span a broad range of chemical classes and routes of exposure. Importantly, levels and intentional use of these toxicants can vary across communities and regions.
Epidemiological research traditionally focuses on single environmental exposures. The burden of cumulative, or simultaneous, environmental exposures on diabetes risk has not been systematically examined. To capture multifactorial ambient environmental exposures, the Environmental Quality Index (EQI) was developed. The publicly available EQI is a county‐level measure of cumulative ambient environmental exposures for the USA for the period 2000–2005 New research set out to examine if environmental factors in rural and urban areas also play a role. Dr. Jyotsna Jagai, a research assistant professor of environmental and occupational health sciences at the University of Illinois at Chicago School of Public Health, is the first author of the new study. With his team, he examined people in 3,134 counties across the USA and published their findings in the Journal of Diabetes Investigation. 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 the quality of the air, water, and land, as well as sociodemographic factors in a given area.
Sociodemographic factors included average household income, education, violent crime rates, or property crime rates. The EQI also included so-called built domain factors. That is, how many fast-food restaurants were in an area, how many fatal accidents occurred, and how many highways, roadways or public housing units there were. The results of this analysis showed that overall, a poorer environmental quality had links with a higher prevalence of type 2 diabetes. The research linked inferior air quality and built and sociodemographic factors with a higher risk of diabetes in rural areas. However, in urban areas, the researchers associated only air and socio-demographic factors with diabetes risk. Dr. Robert Sargis, study co-author and UIC associate professor of endocrinology, diabetes, and metabolism in the College of Medicine, explains the scientific value of using the EQI: “The EQI’s cumulative assessment is unique. In most studies, we are not looking at the combination of factors. We look at single chemicals or single classes of chemicals and how they are associated with disease risk. This study pulls together all of the factors we think increase risk and puts them into a single measure to look at the cumulative environment”.
The authors mention that the findings confirm previous studies that found an increased risk of diabetes in urban areas with poor air quality, or studies that showed changes in air quality might raise insulin-resistance. But they think environmental influence is so much more than pollution.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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