Air pollution and diabetes are responsible for millions of death globally.
Air pollution is a global issue, but low-income cities are the most affected.
The air quality database — which was updated in 2018 — shows that more than 80 percent of people who live in urban areas breathe air that does not meet the WHO guidelines.
Diabetes is a chronic disease that occurs when the body's ability to produce the hormone insulin is reduced, leading to high blood sugar levels. Diabetes can be treated, but complications can lead to kidney failure, heart disease, and stroke.
Data from the WHO show that in 2014, 8.5 percent of adults developed diabetes, and that in 2015, this health condition resulted in 1.6 million deaths.
Diabetes and air pollution
Researchers at Washington University School of Medicine in St. Louis, MO — in collaboration with the Veterans Affairs St. Louis Health Care System in Missouri — found a strong link between air pollution and diabetes.
This could help to bring new awareness of the harmful effects of poor air quality. The study was published recently in The Lancet Planetary Health.
For the study, the team of scientists analyzed the impact of pollution on a group of United States veterans with no previous history of diabetes.
They followed these participants for a median of 8.5 years. They used a variety of models, which they tested against other parameters, such as ambient air sodium concentrations and lower limb fractures.
The researchers used these additional variables — which are not associated with diabetes or air pollution — to eliminate the chances of measuring a false relationship.
Based on these analyses, they estimate that globally, air pollution contributed to around 3.2 million cases of diabetes and the loss of 8.2 million years of healthy life in 2016. This last figure represents about "14 percent of all years of healthy life lost due to diabetes" due to all causes.
"Our research shows a significant link between air pollution and diabetes globally. We found an increased risk, even at low levels of air pollution currently considered safe by the U.S. Environmental Protection Agency (EPA) and the WHO."
Senior author Dr. Ziyad Al-Aly
He goes on, "This is important because many industry lobbying groups argue that current levels are too stringent and should be relaxed. Evidence shows that current levels are still not sufficiently safe and need to be tightened."
How does pollution lead to diabetes?
The exact mechanism behind the relationship between air pollution and diabetes has not yet been proven. However, scientists know that some pollutants — once they have been breathed in — can enter the bloodstream and interact with tissues and organs.
These interactions ultimately disrupt the body, and, among other things, may alter insulin sensitivity and production.
It is important to note that the risk of pollution-related diabetes is higher in lower-income countries that lack clean air policies, such as India, China, and Indonesia, while more wealthy countries, such as Canada, Australia, and New Zealand, have a lower risk.
The study findings suggest that the risk of diabetes rises dramatically between the lowest possible exposure levels and the EPA guidelines for air quality standards.
In other words, even at levels that are officially deemed "safe," the risk is still significant. In October 2017, the Lancet Commission on pollution and health published a report highlighting the harmful effects of pollution.
This new study, which aimed to find new evidence, uncovered proof that pollution can have an even greater impact on health, possibly leading to the development of diabetes.