Functional and metabolic burden of air pollution: relevance of early disease (prediabetes) stage for progression to overt diabetes mellitus

The growing burden of diabetes mellitus has raised interest in uncovering disease susceptibility factors, in order to contain further increases in the burden (1). It is currently admitted that both genetic and environmental factors play a critical role in the disease occurrence and progression. Besides the traditional diabetes risk factors such as unhealthy lifestyles, obesity, and family history of diabetes, interest for emerging factors such as ambient air pollutants, has significantly increased in recent years. This is reflected in a number of studies recently summarized by our group and other investigators (2-4). While existing studies suggest a modest effect of exposure to ambient air pollutants on diabetes risk, the underlying mechanisms largely remain elusive. With regard to type 2 diabetes, the progression to clinically overt disease is determined by the interplay between insulin resistance and alteration of beta-cell secretory capacity (5). It has been suggested that air pollutants could possibly interfere with these pathophysiological derangements either directly or via multiple pathways including endothelial dysfunction, systemic inflammation, dysregulation of visceral adipose tissue, mitochondrial dysfunction, non-alcoholic steatohepatosis, among others (6).