Could our car-dependent way of life be contributing to the global chronic health issue of diabetes? Researchers have found a link between airborne pollution and diabetes, raising questions about the need to plan greener cities for healthier outcomes.
O verweight. Obesity. Not doing enough exercise. These are just a couple of contributors to the risk of developing diabetes, one of the most prevalent chronic conditions in the world.
The problem is that focussing exclusively on these factors not only perpetuates stigma, but also narrows the options we have to address diabetes, harming our chances of beating it.
Researchers at the University of Wollongong (UOW) argue that we need to think outside the box, pointing towards a new study focussing on the condition’s causes: air pollution.
The study highlights a form of prevention that doesn’t come from the GP, but from urban planners and the private sector, and also points towards the importance of green space in our suburbs.
The study was conducted by an international team of scientists involving Associate Professor Thomas Astell-Burt, Founding Co-Director of the Population Wellbeing and Environment Research Lab (PowerLab) at UOW, and led by Dr Liyuan Han of Ningbo University Medical School.
Type 2 diabetes is complex and isn’t caused by one particular thing, and if we can better understand the triggers then we can find solutions that make a difference.Associate Professor Thomas Astell-Burt
Globally 452 million people have diabetes, according to the International Diabetes Federation. It occurs when the pancreas is unable to make insulin or cannot make good use of insulin it produces.
Type 2 diabetes is the more common type of diabetes and unlike type 1, is considered preventable with diet and exercise. Both, if not well managed, can lead to serious complications including kidney disease, nerve damage, heart disease and blindness.
However, Professor Astell-Burt, who regularly visits China for research as part of his adjunct professorial appointment in population health and environment with Peking Union Medical College and the Chinese Academy of Medical Sciences, says the study demonstrates the simplistic ‘lifestyle’ tag that has stigmatised type 2 diabetes for decades has been oversimplifying the true picture.
“Type 2 diabetes is complex and isn’t caused by one particular thing, and if we can better understand the triggers then we can find solutions that make a difference,” he says.
The longitudinal study, part of which was published in the American cardiovascular journal Circulation, ran from 2008 to 2015. It was set in Ningbo in Zhejiang Province, an economic centre and coastal city comprising 7 million people.
It is one of the many areas of China that face a type 2 diabetes epidemic with a national prevalence that has risen from 0.06 per cent in 1980 to 10.9 per cent in 2013. In some of its heavily polluted cities, levels of dangerous emissions are 30 times higher than recommended by the World Health Organization.
The study focused on pollutants that included sulphur dioxide, nitrogen dioxide and microscopic particulate matter (PM 10 and PM 2.5) consisting of dust, soot, smoke, pollen and liquid droplets.
Diabetes: the world’s fastest growing chronic condition
In 2017 an estimated:
- 9 million people had diabetes
- 4 million deaths were due to diabetes
- 79 per cent of adults with diabetes live in low and middle-income countries
Worldwide By 2045:
- One in 10 adults will have diabetes (629 million people)
- Diabetes-related health expenditure will exceed USD$776 billion
Source: IDF Diabetes Atlas 2017
More than 25,000 newly diagnosed type 2 diabetes cases were included in the study. It not only found that long-term exposure to high levels of sulphur dioxide and particulate matter (PM10) were positively associated with type 2 diabetes, but also the effects were stronger for females, compared with males.
“What differentiates our study from many others was that we were able to look at exposure of many air pollutants over a long period of time,” Professor Astell-Burt says.
The observational study took into account environmental conditions including the season, temperature, humidity and wind speed.
Intriguingly, the smaller particulate matter (PM 2.5) which is considered more dangerous due to the fact it is more easily absorbed into the body, was not linked to developing type 2 diabetes. However, it has been shown to be harmful for other health conditions.
It is thought that the identified pollutants once absorbed into the lungs, blood stream and organs, trigger an inflammatory action in the pancreas that impacts on insulin production.
Unfair and unjustified stigma
Michelle Robins, a nurse educator with Australian Diabetes Educators Association, says research of this type will be welcomed by people who have felt shame over their diagnosis.
She says the profile of those now diagnosed with type 2 diabetes is becoming a lot broader to include people as young as teenagers which suggests cause goes beyond just poor diet and lack of exercise in middle age.
Yet the stigma remains.
“People will say things like ‘you got it because you sat on the couch and ate KFC and now you expect my taxes to pay for you’,” Ms Robins says. “I’ve had people say they’ve had more negative feedback from other people than when they used to smoke.”
Prevention and treatment
Professor Astell-Burt says while the precise physiology that explains how air pollution of the type studied impacts on insulin production is still uncertain, the results give a clear direction for positive change.
“Even low levels of air pollution like what we have in Australia are linked with multiple harms to our health, so we must find solutions,” he says. “There is no silver bullet … but research being done by my students, Professor Xiaoqi Feng and I at the PowerLab with its focus on built environment and the health benefits of urban greening includes investigating ways in which we can protect people from air pollution.
“Green spaces can range from something as majestic as Centennial Park in Sydney, all the way through to tree-lined streets that provide canopy and green walls.”
Professor Astell-Burt and Professor Feng’s research has found children in Australia in areas with heavy traffic have lower odds of developing asthma if there is an adequate amount of green space nearby.
We’ve found adults who live near green space in New South Wales can help reduce the odds of developing type 2 diabetes by as much as 10 per cent.Associate Professor Thomas Astell-Burt
“The green space may help trap air pollution while also putting us at a greater distance from the traffic,” he says. “We’ve found adults who live near green space in New South Wales appears to help reduce the odds of developing type 2 diabetes by as much as 10 per cent.
“I’m now very interested in the potential for urban greening to help us age healthily, preventing cognitive and functional decline and maybe even helping to prevent Alzheimer’s disease.”
Professor Astell-Burt is thinking in terms of prevention as well as treatment. As well as cleansing the air and diluting pollution, green spaces can provide inviting places for activity and exercise, components vital for preventing and managing diabetes.
“For a person with the condition, eating healthily is important but keeping an active and social lifestyle is also key,” he says. “Our NHMRC-funded research is showing that all of these things are much easier to do in an area designed to encourage and enable wellbeing.”
Diabetes and psychological wellbeing
He agrees the hard-to-budge stigma of type 2 diabetes is a heavy burden for many people and can lead to depression and social isolation. His team did research on more than 26,000 people between 2006 and 2010 to gauge over time how their diagnosis impacted on their psychological wellbeing, social contacts and quality of life.
It found diagnosis was implicated in a fivefold increase in the odds of reporting life quality as poor, which may be explained by the reduction in social contacts that was also observed.
Professor Astell-Burt says this body of work supports opportunities for change that will need government support at every level.
There are areas in Western Sydney where the prevalence of type 2 diabetes is above the national levels, and we know these are areas where communities experience an awful lot of health and societal economic-related difficulties.Associate Professor Thomas Astell-Burt
He applauds the NSW Government’s recent commitment to spend $290 million dollars in restoration of green spaces within Sydney but says the first thing he would be asking is where that money is to be spent.
“Wealthier suburbs in many Australian cities tend to have more than adequate levels of green space,” says the professor.
“But there are areas in Western Sydney where the prevalence of type 2 diabetes is above the national levels, and we know these are areas where communities experience an awful lot of health and societal economic-related difficulties.”
Professor Astell-Burt says targeting green space restoration and improvements in these communities may have a disproportionately greater benefit in helping to address a range of health challenges, including type 2 diabetes, in comparison to neighbourhoods where other resources are already available.
“This question of where investment in green space is to be made is very important if we value a fair and healthy society,” he adds.