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Ambient air pollution exposure tied to diabetes risk in children with overweight, obesity
Prolonged ambient exposure, particularly exposure to nitrogen dioxide and particulate matter with aerodynamic diameter less than 2.5 µm, increases the risk for development of type 2 diabetes in Hispanic children with overweight or obesity, study data show.
“While type 2 diabetes has been strongly linked with obesity, poor diet and low physical activity, our study demonstrates that there is likely a substantial contribution to the development of type 2 diabetes from environmental exposures that is independent from obesity,” Michael I. Goran, PhD, co-director of the Diabetes and Obesity Research Institute at Keck School of Medicine, University of Southern California, Tanya L. Alderete, PhD, a postdoctoral research scholar, division of environmental health, department of preventive medicine, Keck School of Medicine, University of Southern California, told Endocrine Today.
Goran, Alderete and colleagues evaluated Hispanic children (mean age, 11.3 years; 58% boys) with overweight or obesity at high risk for developing diabetes, from Los Angeles, enrolled between 2001 and 2012 and followed for a mean of 3.4 years. Researchers sought to determine the effects of nitrogen dioxide (NO2) and particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) on measures of insulin sensitivity, beta-cell function and obesity.
After adjustment for confounders and body fat percent, higher NO2 and PM2.5 exposures had adverse effects on the development of risk factors for type 2 diabetes, including insulin sensitivity, acute insulin response to glucose and disposition index. Beta-cell function fatigue was also evident with prolonged exposure to ambient air pollution.
After adjustment for confounders and body fat percent, elevations in fasting and 2-hour insulin levels were associated with increased long-term average ambient air pollution.
At age 18 years, a 5% increase in body fat was associated with 16.7% lower insulin sensitivity (P < .001), 10.2% higher acute insulin response to glucose (P < .001), 30% higher fasting insulin (P < .001) and 6.9% lower disposition index (P = .01).
“Our findings indicate that increased ambient air pollution exposure contributes to risk factors for type 2 diabetes in Hispanic youth living in an urban environment,” Alderete and Goran told Endocrine Today. “In order to successfully reduce the incidence and burden of this disease, these environmental exposures should be considered in conjunction with traditional risk factors such as obesity, diet and exercise. Furthermore, interventions to further reduce air pollution levels have numerous health benefits to children and adults including reduction in heart disease and lung disease.” – by Amber Cox
For more information:
Tanya L. Alderete, PhD, can be reached at tanya.alderete@usc.edu.
Michael I. Goran, PhD, can be reached at goran@usc.edu.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to TopIn this longitudinal study, Alderete and colleagues assessed the effects of ambient air pollution exposure on risk factors for type 2 diabetes in 314 high-risk overweight and obese Latino children (aged 8 to 15 years) residing in urban Los Angeles, California.
The authors showed that higher ambient air pollution exposure had adverse effects on insulin sensitivity, insulin secretion and beta-cell function and that there were linear associations in these adverse effects over the 3-year follow-up period, suggesting a dose-dependent effect on these important risk factors for incident type 2 diabetes. Higher exposure was also associated with more rapid increases in BMI and other measures of adiposity, and these associations were stronger among girls, suggesting sex differences in vulnerability to these adverse effects. The study has several limitations, including no control lean group and no data on the interaction with diet and physical activity. However, this longitudinal study strongly supports previously published cross-sectional studies implicating ambient air pollution exposure as a significant factor in the incidence of type 2 diabetes. Future studies should include appropriate control populations and might include investigation of cohorts where exposure has significantly changed over time.
Diabetes disproportionately affects Latinos in the United States, and it tends to strike this population at younger ages than in the white population. Identifying nontraditional and modifiable risk factors for dysglycemia that start early in life will not only add to our knowledge of the complex pathophysiology of type 2 diabetes, but will influence the development of public health policies to address the effect of air pollution and reduce health disparities in obesity and type 2 diabetes.