When a recent study found higher air pollution exposure led to faster progression towards diabetes, Dr Anurag Agrawal, dean of Ashoka University, flagged concern about how every bit of increase in exposure to air pollutants matters for our health.
“It is not my purpose here to bemoan any single cause of air pollution – whether transient, such as crop burning by farmers or cracker bursting at Diwali; or perennial, such as vehicular emissions, garbage burning, construction, amongst others. The key point is that every bit of increase in exposure, and by corollary every decrease, matters for our own health,” Dr Agrawal, BioSciences and Health Research, Trivedi School of Biosciences, told The Indian Express.
A recent study from Delhi and Chennai in over 12,000 people found that higher air pollution exposure led to faster progression towards diabetes. This is consistent with previous observations in western nations, but acquires a much higher sense of urgency in the Indian situation, particularly that of Delhi.
How modest air pollution control may reduce prevalence of adult diabetes?
It would not be an exaggeration to compare the current diabetes-control situation to trying to extinguish a burning fire by throwing a glass of water while a can of petrol continues to be poured on it, Dr Agrawal says.
“Of course, air pollution is just one of many components of this petrol, but an important one that is not emphasized enough. In the study, medium-term exposure of over six months to a 10 μg/m3 change in airborne particulate matter was associated with about 0.7 mg/dl increase in fasting glucose and 0.03 unit increase in HbA1c. In a somewhat oversimplified but still useful analogy, an average person with pre-diabetes moves about 5 per cent of the remaining distance to diabetes with every such unit (10 μg/m3) increase in air pollution,” Dr Agrawal explains.
Winter pollution in Delhi can easily be ten times of this and is even more near Diwali. Although that is a very short-term exposure, the effect of which was not studied here, he says.
“Using more complex models, the authors estimated that about half of all new diabetes seen during the study was attributable to air pollution and that even modest air pollution control may reduce the prevalence of adult diabetes by 1-2%. In a metro of about 15 million adults, that is a very big number and even after accounting for possible model errors, it remains a big number,” he adds.
On air pollution and health concerns
Earlier this year, the results from the Indian Council of Medical Research–India Diabetes (ICMR- INDIAB) study, the largest nationally representative population-based study on diabetes, showed that about 10 per cent of adults already had diabetes and 15 per cent had pre-diabetes.
One of the important lessons that came from this study was the urgent need of measures to prevent or slow progression from pre-diabetes to diabetes that is otherwise likely to occur within five years. This will be challenging since the path to diabetes in India is somewhat different from the west where obesity and insulin resistance are the key drivers.
Diabetes prevalence was high across India in the ICMR-INDIAB study, including in regions with better air. Clearly sedentary lifestyles, unhealthy food habits, and obesity remain prime risks that should not be ignored. However, there are a few reasons to give importance to the link to air pollution. First, it is not an individual choice. Second, it is about much more than diabetes alone. Multiple common diseases including asthma, COPD, hypertension, are caused or exacerbated by air pollution. “We will live longer than any previous generation, but it is likely that respiratory diseases and the complications of diabetes and hypertension, ranging from the well- known such as heart attacks or kidney failure, to the less well-known such as accelerated cognitive decline and dementia, may make this a curse rather than a blessing, Dr Agrawal said.
Medications and measures
Weight loss or exercise work well in people with insulin resistance due to obesity. Indian diabetes, in contrast, has a major component of low insulin production that is thought to be due to multi-generational nutritional scarcity and environmental toxins. This is more difficult to manage and may progress to requiring insulin injections. “In my opinion the best long-term way to reduce high Indian risk of diabetes is to act on early-life factors that are operational ever since we are in the womb. Improving our environment with special attention to air is important,” Dr Agrawal said.
