Long-term exposure to PM2.5 linked to 10-16 pc higher risk of Type 2 diabetes: Study

Longterm exposure to fine particulate matter PM25 is associated with a 10 to 16 per cent higher risk of developing Type 2 diabetes for every 10 microgram per cubic metre increase in exposure according to a global review of research published in the Journal of Vascular DiseasesThe findings published ahead of World Diabetes Day on November 14 are based on an umbrella review of 13 systematic reviews and metaanalyses covering more than 200 million cumulative participant observations from studies across different parts of the worldThe review titled Association Between PM25 Exposure and Type 2 Diabetes Across the CardiovascularKidneyMetabolic CKM Continuum APEXT2D has been coauthored by Dr Anoop Misra Executive Chairman and Director Diabetes and Endocrinology Fortis CDOC Hospital New DelhiThe researchers found that six of the seven reviews examining new cases of Type 2 diabetes reported an increased risk ranging between 10 and 16 per cent for every 10 microgram per cubic metre rise in longterm PM25 exposureThe association was observed across Asian and Western populations with the findings also indicating a doseresponse relationship wherein the risk increased with higher levels of exposurePM25 refers to fine particulate matter with a diameter of less than 25 micrometres which can penetrate deep into the lungs and trigger responses beyond the respiratory systemThe researchers said possible biological pathways linking air pollution to diabetes include systemic inflammation oxidative stress endothelial dysfunction and impaired insulin signalling However these mechanisms remain incompletely understoodThe review also found positive associations between PM25 exposure and the prevalence of Type 2 diabetes diabetesrelated mortality and fasting blood glucose levels However the evidence for these secondary outcomes was rated very lowThe researchers cautioned that the findings establish an association rather than a direct causeandeffect relationship The evidence for the increased incidence of Type 2 diabetes was rated as being of low certainty given the observational nature of the studies and substantial variations in their findingsThey also noted that the more than 200 million figure represents cumulative participant observations across the reviews and not 200 million unique individuals as several reviews included overlapping studies and populationsThe association was also reported in populations with annual average PM25 exposure levels around 5 to 7 micrograms per cubic metre close to the World Health Organisations annual guideline of 5 micrograms per cubic metre However the review did not establish a safe threshold for exposureHighlighting the public health implications the researchers said air pollution should be considered as part of cardiometabolic disease prevention strategies particularly in South Asia where high pollution levels coincide with a growing burden of metabolic disordersThey called for greater airquality monitoring the inclusion of air pollution in diabetes prevention and research frameworks and more longterm studies to establish whether reducing exposure can lower the incidence of diabetesThe researchers however said existing evidence does not establish that a specific reduction in PM25 exposure would lead to a proportional decline in diabetes casesType 2 diabetes which affects more than 500 million adults globally is commonly associated with factors such as obesity physical inactivity dietary habits and genetic susceptibility The review adds longterm environmental exposure to the growing body of research examining factors associated with the disease