Pollution is bad for our health in so many ways, but you may be surprised to know that it’s also bad in the context of diabetes.

If you’ve ever been to a place where the air was so congested that your eyes watered, you’ve experienced the most immediate effects of air pollution. Just recall last summer when the Northeast of the U.S. was enveloped in an orange fog from smoke flowing down from Canadian wildfires, causing very unhealthy, hazardous air quality, leading for the first time to a “code purple”, or “very unhealthy,” ranking from the U.S. Environmental Protection Agency’s Air Quality Index. 

That was extreme, but poor air quality is something people across the country contend with regularly. In fact, the American Lung Association’s “State of the Air” 2023 report has found that nearly 36 percent of Americans — or almost 120 million people — are still living in places with unhealthy levels of ozone or particle pollution.

While we usually think of diabetes as a disease of genetics and/or nutrition the environment and the air we breathe can also impact the development and progression of type 1 and type 2 diabetes.

Numerous studies over the past 20 years have investigated the connection between air pollution and diabetes both in the U.S. and in other countries. They’ve found that exposure to air pollution can contribute to the onset of diabetes and can cause health complications for those who already have diabetes.

Give the Culprit a Name: Particulate Matter

When we’re talking about air pollution, we’re specifically talking about particulate matter. Some particulate matter you can see. A mix of solid particles and droplets, it’s found in wildfire smoke, of course, but also dirt and dust, and soot from fireplaces to industrial output. Also dangerous is the particulate matter we can’t see,  so miniscule it requires a special microscope. 

Particulate matter is generally classified according to size: PM10 particles, which have diameters of 10 micrometers and less, and PM2.5, which have diameters of, yes, 2.5 micrometers and less. The EPA offers a comparison to a single human hair, which has a diameter of about 70 micrometers. 

Particulate matter is comprised of hundreds of different chemicals, and can come from everything from construction sites, smokestacks, and fires to fields and unpaved roads. And let’s not forget tobacco smoke. Most pollution forms in the atmosphere due to reactions between chemicals such as sulfur dioxide and nitrogen oxides. These pollutants spew from power plants, industrial and manufacturing factories, and vehicle emissions. 

In the United States, the most polluted areas tend to cluster near major cities like Los Angeles; the air quality in the densest areas of Asia and Africa is considerably worse.

How Exposure to Particulates Leads to Diabetes Risks

There have been dozens of studies since at least the early 2000s that have examined the connection between pollution and type 2 diabetes. A 2019 review of the literature concluded that “type 2-related biomarkers increase with increasing exposure duration and concentration of air pollutants.” 

A 2020 study in Korea found that fasting blood glucose and A1C levels both got significantly worse after exposure to pollution — especially in adults with diabetes.

How would particulates potentially affect the development or progression of type 2 diabetes? There are multiple explanations. It appears that they increase inflammation and oxidative stress, which are associated with type 2 diabetes risks.

The researchers also explained that studies have shown that air pollutants may be associated with impaired glucose metabolism and insulin resistance. Exposure to particulate matter can induce the release of cytokines and other inflammatory factors that lead to reduced insulin sensitivity and block the uptake of glucose in tissues, which, in turn, can increase the risk of type 2 diabetes. 

Another factor could be that air pollution can affect the gastrointestinal tract. A 2020 survey pointed out that exposure to air pollutants is associated with reduced bacterial diversity. That disturbance to the gut microbiome has been linked with obesity and type 2 diabetes. Air pollution exposure is linked to obesity; one study has even found that “infants whose mothers lived close to a major roadway at the time of delivery may be at later risk for adverse cardiometabolic health.”

Pollution may also affect diabetes outcomes indirectly. We are less likely to get outside and exercise, for example, if the air is unpleasant to breathe.

Because many studies show that African Americans are exposed to more air pollution than white Americans, it may be that pollution, particularly in the form of ozone, may contribute to the higher incidence of diabetes among African Americans.

Air Pollution and Type 1 Diabetes?

If air pollution can affect glucose metabolism, then it might also affect the blood sugar management of people with type 1 diabetes. A 2021 study from Germany, for example, found that children exposed to a greater degree of air pollution were more likely to suffer from both high A1C levels and dangerous hypoglycemic events.

In fact, air pollution might even contribute to the development of type 1 diabetes in the first place. With type 1 diabetes rates increasing across the globe, experts have long suspected that the condition can be triggered by subtle environmental (non-genetic) changes. Researchers have investigated milk, baby formula, drinking water, exposure to sunshine, and a myriad of other variables in the search for mechanisms that might spark the type 1 diabetes autoimmune attack.

Back in the early 2000s, it had been shown that increased exposure to ozone may be a contributing factor to the increase of type 1 diabetes. A 2002 paper identified PM10 as a potentially significant contributing factor to the development of type 1 in children under age 5. A 2006 study attributed exposure to air pollutants, specifically passive smoking in the household, as a factor that would precipitate or accelerate the onset of type 1 in children. 

Scientists speculate that the direct effects of pollution on beta-cell function could be a mechanism in the polluting chemical that contributes to autoimmunity. These could be related to altered mitochondrial functions and the onset of oxidative stress, or even impaired beta-cell replication. 

The challenge is that there’s so much complexity around human exposure to environmental chemicals that scientists can’t yet pinpoint a single factor that leads to type 1. The specific molecular mechanism is elusive, but scientists believe that the data indicate that the issues they cause—air pollution-induced inflammation and oxidative stress—are significant components leading to type 1 diabetes.

How Can Environmental Factors Impact the Health of People with Diabetes?

It’s not enough to look at how pollution could lead to diabetes. We also have to address how it can impact the health of those who already live with the condition. 

The EPA put out a fact sheet on this very topic. The bottom line is that people with diabetes who are exposed to air pollution are at increased risk of heart attack and stroke. In fact, a study published back in 2002 found that people with diabetes have double the risk of a PM10-associated cardiovascular admission to hospital. The researchers made a connection between pollution and elevated white cell counts and increased concentrations of c-reactive protein in plasma. This is significant since c-reactive protein is a marker for inflammation associated with heart attacks and death.

And it’s not just smog or other industrial-related air pollution. Wildfires, which are now more frequent as a result of climate change, are a potential source of fine particulate matter that can have adverse impacts on people with diabetes.

Ways to Minimize Pollution Exposure

Given the risks of air pollution to health, particularly for people with diabetes, it’s important to reduce exposure as much as possible. Here are some tips garnered from experts including the EPA, the California Air Resources Board, the Journal of Thoracic Disease, the American Lung Association,  and AirNow.gov :

Pay attention to Air Quality Index forecasts.
Stay inside on high-pollution days and keep windows closed. 
Put your air conditioner in recirculation mode on high-pollution days to keep indoor air clean. In general, make sure your HVAC system filters are clean.
Keep your home clean to avoid the circulation of pollutants in carpets, area rugs, and hard floors. Use a high-efficiency vacuum cleaner.
Use an air purifier with a HEPA filter. 
Avoid tobacco smoke.
Identify and address areas where ventilation is inadequate, like bathrooms and kitchens, which generate moisture that leads to mold and dust mites. Make sure you have and use clean fans in these rooms. Also inspect and address ventilation for gas heaters, fireplaces, wood-burning stoves, and space heaters that generate particulate matter.  
On high-pollution days limit outdoor physical exertion and generally avoid exercising near busy streets and freeways.
Consider wearing an air-purifying respirator, such as an N95 mask, when pollution is at its worst. 

Editorial Sources & Fact-Checking