Regular physical activity reduces risk for type 2 diabetes, independent of pollution
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Adults who routinely engage in a high level of physical activity may be able to reduce their risk for developing type 2 diabetes, even in areas with high air pollution, according to a study published in Diabetologia.
“Regular physical activity is a safe approach for people living in polluted areas to prevent diabetes,” Xiang Qian Lao, BMed, PhD, associate professor at The Jockey Club School of Public Health and Primary Care at the Chinese University of Hong Kong, told Healio. “Air pollution increases the risk of diabetes, but does not override the benefits of regular physical activity on diabetes prevention. Air pollution mitigation is important for diabetes prevention.”
Lao and colleagues collected data from an ongoing large prospective cohort study in Taiwan. In the study, adults aged at least 18 years visited the MJ Health Management Institution in Taiwan for a series of medical examinations at baseline and regular follow-up. Adults without type 2 diabetes at baseline who had plasma glucose measurements and fine particulate matter levels available between 2001 and 2016 were selected for the study. Participants reported details of their weekly physical activity in a questionnaire, with intensity classified as light, moderate, medium-vigorous or high-vigorous. The weekly time spent performing physical activity was also collected. Two-year mean fine particulate matter concentrations were estimated for each participant’s address based on latitude and longitude data. Pollution was measured using aerosol optical depth data from the Moderate Resolution Imaging Spectroradiometer installed in U.S. NASA satellites.
Of the 156,314 study participants, 5,305 developed type 2 diabetes during a mean follow-up of 5.2 years. In an adjusted model, researchers observed an increased risk for developing type 2 diabetes among participants who engaged in moderate physical activity (adjusted HR = 1.31; 95% CI, 1.22-1.41; P < .001) and low physical activity (aHR = 1.56; 95% CI, 1.45-1.68; P < .001) compared with those who performed high levels of physical activity. Participants exposed to moderate levels of pollution (aHR = 1.31; 95% CI, 1.22-1.4; P < .001) or high levels of pollution (aHR = 1.94; 95% CI, 1.76-2.14; P < .001) also had a higher risk for type 2 diabetes compared with people exposed to low pollution levels.
Researchers noted that while the measurements of physical activity and pollution were not comparable in the study, data suggest the pollution level’s association with diabetes was slightly stronger.
“I am surprised with the finding that air pollution has a stronger association with diabetes than ... regular physical activity,” Lao said. “That means air pollution mitigation is more efficient for diabetes prevention.”
In subgroup analysis, participants performing a high level of habitual physical activity had lower risk for developing type 2 diabetes compared with those participating in moderate or low levels, regardless of the level of pollution. Similarly, moderate and high levels of pollution increased the risk for type 2 diabetes compared with low pollution, regardless of how much physical activity was performed. The risk for developing type 2 diabetes for a person with high habitual physical activity exposed to low pollution levels was 64% lower than for a participant with low physical activity exposed to high amounts of pollution.
Lao said future research should examine the effects of physical activity in polluted areas on other health outcomes, including hypertension, lung disease, dyslipidemia, chronic kidney disease and mortality. He also said research should be done in other regions, including ones with higher pollution levels.
For more information:
Xiang Qian Lao, BMed, PhD, can be reached at xqlao@cuhk.edu.hk.
Perspective
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Roeland J.W. Middelbeek, MD, Msc
Regular physical activity and exercise play a key role in both the prevention and treatment of type 2 diabetes. Conversely, low levels of physical activity and, more recently, air pollution have been identified as contributing factors to the development of type 2 diabetes.
A new study from Cui Guo and colleagues aims to dissect whether regular physical activity alters the risk of type 2 diabetes imposed by air pollution. Using physical activity questionnaire data and satellite-based estimates of air pollution, they find that higher levels of air pollution as well as lower levels of physical activity associate with increased risk of type 2 diabetes. They conclude that even in highly polluted areas, physical activity reduces the risk of type 2 diabetes and remains a safe strategy.
This is encouraging news as, by increasing physical activity, people can take charge and reduce their risk of developing type 2 diabetes. At the same time, governmental and regulatory efforts to reduce air pollution are also desperately needed to reduce the burden of air pollution on overall health.
A number of questions remain about the mechanisms by which air pollution affects diabetes risk. Air pollution has been suggested to affect systemic inflammation and oxidative stress. Future research will need to determine whether the effects of air pollution on inflammation are directly prevented or reversed by regular physical activity or may be mediated by different mechanisms. In the meantime, people at risk for diabetes should be encouraged to remain physically active, even in highly polluted areas.
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