When you think risk factors of diabetes, what comes to mind?

Obesity? Junk food? High blood pressure and cholesterol? A sedentary lifestyle?

What about air pollution?

Apart from the classic variables, mounting research in recent years points to a strong causal link between diabetes and what might have seemed like an unlikely culprit.

How exactly does air pollution cause and worsen diabetes?

FIT spoke to Dr Ambrish Mithal, chairman and head of Endocrinology & Diabetes at Max Hospital, New Delhi, and Prof K Srinath Reddy, president of the Public Health Foundation of India.

India is considered the 'diabetes capital of the world', and the alarming statistic is only second to the alarming pollution levels in the country–also some of the highest in the world.

And as it seems, the latter may have a strong hand in the onset of diabetes, but also in aggravating the condition.

"Even in prediabetic states, you have a higher degree of vascular damage and organ damage, whether it is the heart or the kidney," says Prof Srinath Reddy, president of the Public Health Foundation of India.

Speaking of one of the most polluted cities in the country, Delhi, Prof Reddy continues,

'Diabetes in India is moving from villages to cities.'

There is a possibility that this could be in part at least attributed to higher levels of pollution in cities as compared to villages.

There is evidence to suggest air pollution also increases the risk of severe complications and even fatality in patients of diabetes, points out Dr Ambrish Mithal.

"Basically the pollution that matters largely is the PM 2.5 – the small particles. Most studies do indicate that air pollution of PM 2.5 increases the risk of diabetes, and the risk of dying from diabetes," he says.

One of the studies Dr Mithal talks of— published in the Lancet Planetary Health in 2018—found that the risk of incident diabetes (and death) increased with an in crease in the concentration of PM2.5 pollutants.

Moreover, the numbers were found to be heavily skewed towards low and middle income countries, including India.

Why exactly, PM 2.5? It's difficult to say for certain.

Both Dr Mittal and Prof Reddy, however, lean towards inflammation being the prime cause.

"Diabetes is linked, particularly, as a part of the overall body response to air pollution. In places with higher levels of pollution, not only diabetes, but prediabetes, and glucose intolerance is also clearly demonstrated," says Prof Reddy.

Dr Mithal further explains, "inflammation and oxidative stress are thought to be very important in computation with diabetes, and possibly even in development of diabetes."

"PM 2.5 also damages the blood vessel lining, endothelium, as we call it, so endothelial function is also impaired in this," he adds.

On top of this, inflammation resulting from PM 2.5 particles aggravate insulin resistance, which also paves the way for diabetes.

Thirdly, "inflammation actually may even be damaging the pancreatic secretions like the beta cells. And there are some studies to suggest that, (although) that is not finally proven yet," says Dr Mithal.

Air pollution also means less time spent outdoors engaging in physical activity.

This can lead to a domino effect of too much sitting, weight gain, and eventually diabetes, explains Prof Reddy.

The problem is that avoiding air pollution is not as easy as reducing other modifiable risk factos—like controlling your diet or exercising more.

The solution, therefore, is in public policy.

...we just need to implement it right.

"There are a number of multi-sectoral action plans which are already there with the government, what we require is effective implementation," says Prof Reddy.

Some of the areas that require public policy action that he cites are

• Reducing vehicular pollution by imposing better emission standards on the fuels that are being used

• Vehicle density is reduced so that the total emissions is low

• We need to make sure that we're moving away from coal to cleaner energy

• Also moving towards cleaner alternatives available to very highly polluting coals to reduce our dependency on coal

• Agricultural waste and garbage burning, which is another major source should be controlled

• So should there be a control on construction dust in up and coming cities in particular