NEW DELHI: The damage caused by polluted air may not stop at the lungs. Long-term exposure to fine particulate matter (PM2.5), the tiny particles that can penetrate deep into the respiratory system, is also associated with a higher risk of developing type 2 diabetes. The risk was 10% to 16% higher for every 10 micrograms per cubic metre increase in PM2.5 exposure, according to a new global review, raising concerns about the wider health impact of air pollution.Published in the Journal of Vascular Diseases last month, the study analysed 13 earlier systematic reviews and meta-analyses on long-term PM2.5 exposure and diabetes. Six of the seven reviews examining new cases of type 2 diabetes found a 10% to 16% higher risk.The analysis covered studies from North America, Europe, East and South Asia, Latin America and Australia. A South Asian analysis involving populations in India, Bangladesh and Sri Lanka found a 9% higher risk of developing type 2 diabetes for every 10 micrograms per cubic metre increase in PM2.5 exposure.The review also linked PM2.5 exposure to diabetes prevalence, diabetes-related deaths and higher fasting blood glucose, but found no significant association with insulin resistance. Evidence on HbA1c, a measure of average blood sugar, was insufficient.The 13 reviews covered more than 200 million cumulative participant observations, not 200 million unique individuals, as some studies and populations overlapped. One review alone contributed about 198 million observations.
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The study was co-authored by Dr Anoop Misra, Executive Chairman and Director of Diabetes and Endocrinology at Fortis C-DOC Centre of Excellence for Diabetes, Metabolic Diseases and Endocrinology, New Delhi, along with Yashendra Sethi, Nirja Kaka, Saurabh Singhal, Manvi Vasudev and Giuseppe Biondi-Zoccai.“Air quality management must become a core part of diabetes prevention,” Misra said, stressing that air pollution should be viewed not only as an environmental and respiratory health concern but also as a factor in the broader cardiovascular-kidney-metabolic continuum.The researchers said possible mechanisms include inflammation, oxidative stress, impaired blood vessel function and disrupted insulin signalling, which may affect blood sugar regulation. However, these mechanisms were not systematically assessed. They cautioned that the findings show an association, not proof that pollution causes diabetes. Evidence for new cases was graded low, and the review did not establish whether cleaner air would reduce diabetes risk. They called for air quality to be considered in wider efforts to prevent cardiovascular, kidney and metabolic diseases.