How Air Pollution Affects Your Health: New Studies Link Smog to Blood Sugar Changes and Bone Damage

Long-Term Air Pollution Exposure Linked to Higher Diabetes Risk, Indian Review Finds

Prolonged exposure to polluted air may significantly increase the risk of developing type 2 diabetes, according to a new review led by Indian researchers. The analysis found a consistent association between exposure to fine particulate matter and diabetes, with South Asia facing a particularly high public health burden.

A separate study conducted in South Korea has offered possible insights into how pollution could affect people with diabetes. Experiments on mice showed that exposure to polluted air, combined with diabetes, accelerated the ageing of stem cells in bone marrow, potentially weakening the body’s ability to produce blood cells and repair bones.

The findings are particularly relevant to India, where an estimated 10.1 crore people are living with diabetes. With winter approaching, rising levels of fine particulate pollution are once again becoming a concern across several northern Indian cities.

Indian review finds a consistent link between PM2.5 and diabetes
Published on October 27 in the Journal of Vascular Diseases, the Indian-led research is an umbrella review, a type of analysis that brings together findings from previously published systematic reviews. Researchers examined 13 reviews covering more than 200 million participant observations worldwide.

The study was led by Dr Yashendra Sethi of PearResearch, Dehradun, and Subharti Medical College, Meerut. The research team also included Dr Anoop Misra of Fortis C-DOC Centre of Excellence for Diabetes, Metabolic Diseases and Endocrinology in New Delhi, and Saurabh Singhal from the Department of Cardiometabolism at Nexoria Institute of Cardiometabolic Excellence (NICE), Vigyaved Healthcare, Dehradun.

The researchers focused on PM2.5, or fine particulate matter measuring 2.5 micrometres or less in diameter. These particles are around 30 times thinner than a human hair and can penetrate deep into the respiratory system.

All seven reviews that examined new cases of type 2 diabetes reported an association with air pollution. The analysis also indicated that diabetes risk increased with higher pollution exposure, with broadly similar patterns observed in Asian and Western populations.

According to the authors, long-term exposure to PM2.5 was associated with a 10-16% increase in the risk of developing type 2 diabetes for every 10 micrograms per cubic metre rise in concentration. The researchers also found links between polluted air, higher fasting blood glucose levels and increased deaths related to diabetes.

Notably, the association was observed even in locations where annual pollution levels were close to the World Health Organization’s recommended annual PM2.5 limit of 5 micrograms per cubic metre. India’s national annual standard, meanwhile, stands at 40 micrograms per cubic metre.

The researchers highlighted South Asia as a region of particular concern because pollution exposure is widespread and diabetes cases are increasing rapidly. They suggested that air pollution should be considered alongside other risk factors when developing strategies to prevent diabetes and related heart and kidney conditions.

However, the review also acknowledged important limitations. The studies analysed were observational and did not directly establish that pollution causes diabetes. Several reviews also relied on overlapping original research, while the overall certainty of the evidence was rated as low. The authors said that questions of causality and whether the effects can be reversed remain unanswered.

South Korean research explores the impact on bone marrow
A separate study by researchers at Jeonbuk National University in South Korea, published in the Journal of Hazardous Materials, examined how air pollution may affect the body’s repair systems in people with diabetes.

For the research, scientists exposed healthy and diabetic mice to artificial PM2.5 inside a chamber designed to replicate outdoor pollution conditions.

The findings showed that pollution exposure appeared to accelerate the ageing of bone marrow stem cells in diabetic mice. These cells play an important role in producing blood cells and supporting bone repair. Researchers found that the combination of diabetes and fine particulate pollution impaired their functioning.

The damage was linked to an inflammatory mechanism originating in the lungs. Blocking this pathway reversed much of the observed harm in the animal experiments. The researchers concluded that fine particulate matter and type 2 diabetes could act together to intensify biological damage.

Dr Rajeev Jayadevan, convenor of the Kerala IMA’s research cell, cautioned against directly applying the findings to humans.

He pointed out that human and mouse biology differ. He also noted that laboratory animals are sometimes exposed to relatively high pollution doses to produce measurable results within a short period, whereas human exposure generally occurs over many years and at lower doses.

Therefore, he said, the results may not directly translate to humans, although the underlying biological mechanism remains relevant.

Dr Jayadevan added that the harmful effects of air pollution on human health are already well established. Apart from increasing the risk of cancer, hypertension, heart disease and stroke, polluted air can worsen asthma and contribute to neurological conditions, including dementia.

Why the findings are significant for India
The ICMR-INDIAB study, published in 2023, estimated that approximately 10.1 crore people in India have diabetes. Many live in urban areas where PM2.5 concentrations frequently exceed both WHO recommendations and India’s national standards, particularly during the October-to-February winter period.

Dr Kunal Gupta, consultant endocrinologist at Sparsh Hospital, Infantry Road, Bengaluru, said air pollution is increasingly being recognised as an environmental risk factor for type 2 diabetes, alongside established factors such as obesity, unhealthy eating habits, physical inactivity and family history.

He highlighted the review’s finding that every 10 micrograms per cubic metre increase in long-term PM2.5 exposure was associated with an estimated 10-16% higher risk of developing the condition. According to him, the findings are concerning for India because several cities experience persistently high pollution levels.

Dr Gupta also advised people with a family history of diabetes, obesity or other metabolic risk factors to be particularly cautious about prolonged exposure to polluted environments.

While the available research does not establish a direct cause-and-effect relationship in humans, the findings add to growing evidence that long-term air pollution exposure may have consequences beyond respiratory health.