Diabetes has quadrupled in the past four decades, according to the
Centers for Disease Control and Prevention. If the trend continues, one
in three Americans will have diabetes by 2050. Serious complications
blindness, kidney failure, limb amputation or early death.
Latino children who live in areas with higher levels of air pollution
have a heightened risk of developing Type 2 diabetes, revealed a
new USC-led study.
‘Exposure to high levels of air pollution during childhood may make insulin-creating cells become less efficient, increasing the risk of Type 2 diabetes.’
Scientists tracked children's health and respective levels of
residential air pollution for about 3.5 years before associating chronic
unhealthy air exposure to a breakdown in beta cells, special pancreatic
cells that secrete insulin and maintain the appropriate sugar level in
By the time the children turned 18, their insulin-creating
pancreatic cells were 13% less efficient than normal, making
these individuals more prone to eventually developing Type 2 diabetes,
"Exposure to heightened air pollution during childhood increases the
risk for Hispanic children to become obese and, independent of that, to
also develop Type 2 diabetes," said Michael Goran, co-director of the
Diabetes and Obesity Research Institute at the Keck School of Medicine
of USC and corresponding author of the study. "Poor air quality appears
to be a catalyst for obesity and diabetes in children, but the
conditions probably are forged via different pathways."
Published in the journal Diabetes
, the study,
researchers said, is the first to follow children for years to find a
connection between air pollution and diabetes risk in children.
These children lived in neighborhoods that, according to the U.S.
Environmental Protection Agency, had excess nitrogen dioxide and tiny
air pollution particles that are generated by automobiles and power
plants, formally called particulate matter 2.5 (PM2.5).
Researchers found that the beta cells that were still functional
were overworking to compensate for the damaged cells, leading to burn
out. As the cells failed to secrete insulin efficiently, regulation of
sugar in the bloodstream overwhelmed the system, heightening the risk of
Type 2 diabetes.
"Diabetes is occurring in epidemic proportion in the U.S. and the
developed world," said Frank Gilliland, senior author and a professor of
preventive medicine at the Keck School of Medicine. "It has been the
conventional wisdom that this increase in diabetes is the result of an
uptick in obesity due to sedentary lifespans and calorie-dense diets.
Our study shows air pollution also contributes to Type 2 diabetes risk."
Latino children living in polluted areas are at higher risk
Researchers examined the data of 314 overweight and obese Latino
children who were between 8 and 15 years old when they enrolled in the
National Institutes of Health-funded Study of Latino Adolescents at Risk
of Type 2 Diabetes (SOLAR) study, a 12-year undertaking.
Scientists tracked the Los Angeles County children for an average of
3.5 years. None of them had Type 2 diabetes when they enrolled, but
some may have been on the road to the disease toward the study's end.
Each year the participants fasted and then came to the Childhood
Obesity Research Center at USC for a physical exam and to have their
glucose and insulin levels measured over a span of two hours.
When they turned 18, the participants had nearly 27% higher
blood insulin after having fasted for 12 hours. During their two-hour
glucose test, they had about 36% more insulin than normal,
indicating that the body was becoming less responsive to insulin. This
observation illustrated that increased exposure to air pollution was
associated with increased risk factors for Type 2 diabetes.
The researchers adjusted for body fat and socioeconomic status. In
some instances, at age 18, the effect of long-term exposure to higher
air pollution was larger than the effect of gaining 5% body
weight, meaning air pollution is definitely a risk factor for diabetes,
said Tanya Alderete, lead author of the study and a postdoctoral
research scholar at the Keck School of Medicine.
Steps people can take to reduce their risk
The findings suggest that the negative effects of elevated and
chronic exposure to nitrogen dioxide and tiny dirty air particles begin
in early life. If other risk factors such as having an unhealthy diet
persist, then risk for Type 2 diabetes is compounded, researchers said.
"Air pollution is ubiquitous, especially in Los Angeles," Alderete
said. "It's important to consider the factors that you can control --
for example, being aware that morning and evening commute times might
not be the best time to go for a run. Change up your schedule so that
you're not engaging in strenuous activity near sources of pollutants or
during peak hours."
None of the children developed Type 2 diabetes during the study, but
many showed signs that they may eventually develop it and were
characterized as pre-diabetes.
Some 8.1 million people in the United States have diabetes but
haven't been diagnosed, according to the CDC. That means some 28%
of people with diabetes do not even know they have diabetes.
Undiagnosed diabetes raises the risk of afflictions such as stroke,
kidney damage and Alzheimer's disease.
Future studies will also include participants who are not overweight
or obese and should collect data on diet and physical activity,
Findings from this study may be generalized only to overweight and
obese Latino children, mostly of a lower socioeconomic status, according
to the study.