Quantifying the Burden of Air Pollution on Type 2 Diabetes Mellitus in Europe

Air pollution is a significant environmental issue affecting human health, with growing evidence linking it to chronic diseases such as Type 2 Diabetes Mellitus (T2DM). T2DM has become a major global health concern, with its prevalence and incidence rising at an alarming rate. This metabolic disorder, characterized by chronic hyperglycemia due to insulin resistance or insufficient insulin production, has traditionally associated with factors such as obesity, sedentary lifestyles, and dietary habits. However, recent research highlights that environmental exposures, particularly to air pollutants, may significantly contribute to the development and progression of the disease. Particulate matter (PM2.5) and nitrogen dioxide (NO2) have been shown to trigger systemic inflammation, oxidative stress, and endothelial dysfunction—key mechanisms in insulin resistance and beta-cell impairment. These findings emphasize the need to consider air pollution as an emerging and modifiable risk factor for diabetes.

However, the relationship between air pollution and T2DM remains underexplored, with limited studies establishing robust exposure-response relationships. Understanding the exposure-response relationship is crucial for accurately estimating the disease burden attributable to air pollution and guiding public health interventions. this study aims to establish the exposure-response function that relates the concentration of two air pollutants (NO₂ and PM2.5) to the hazard ratio associated with acquiring T2DM, based on various cohort studies conducted worldwide. To achieve this, a methodology using nonlinear function adjustments will be employed, fitting a specific function dependent on four parameters to a scatter plot of pollutant concentration and hazard ratio data pairs extracted from available cohort studies. Once the specific form of this exposure-response function is determined, it will be applied to the domain of Europe using atmospheric concentrations for the period 1991-2020, obtaining the risk ratio for each cell. From there, the incidence of air pollution on T2DM will be estimated for each age group.

The results indicate a significant nonlinear relationship between air pollution exposure and T2DM incidence, with higher risks observed in areas with elevated levels of NO₂ and PM2.5 (specifically, in large European cities and central Europe due to traffic and industrial activities mainly). The results show that NO₂ air pollution is responsible for 4,693,000 [4,285,000 – 4,946,000 95% CI] cases of T2DM per year, representing an incidence of 0.64% [0.58 – 0.67 95% CI] relative to the total population of the study area. For PM2.5, the total number of annual cases rises to 5,009,000 [3,957,000 – 6,452,000 95% CI], accounting for an incidence of T2DM of 0.68% [0.54 – 0.87 95% CI] considering the population in the target area. The analysis revealed that PM2.5, despite lower concentrations compared to NO₂, had a higher impact on T2DM incidence, especially at lower exposure levels. The findings underscore the need for stringent air quality regulations, particularly in urban and industrial regions, to mitigate the health impacts of air pollution.