Environmental toxicant exposures and type 2 diabetes mellitus: Two interrelated public health problems on the rise

Rates of type 2 diabetes mellitus (T2DM) are rising rapidly across the globe and the impact of this devastating disease threatens to plague the 21st century. While some contributing factors are well-recognized (e.g. sedentary lifestyles and caloric excess), other diabetes-promoting risk factors are less established or poorly appreciated. The latter category includes environmental exposures to diabetogenic contaminants. Herein we review some of the latest concepts and mechanisms by which environmental exposures may contribute to rising rates of T2DM with a particular focus on mechanisms involving mitochondrial dysfunction and imbalances in reactive oxygen species (ROS). While the pathogenesis of diabetes includes impairments in insulin sensitivity as well as insulin secretion, we will specifically delve into the links between environmental exposures to toxicants such as arsenic and disruptions in insulin release from pancreatic β-cells. Since β-cell death or dysfunction is at the heart of both T2DM as well as type 1 diabetes mellitus (T1DM), environmental endocrine disrupting chemicals (EDCs) that disrupt the production or regulated release of the glucose-lowering hormone insulin are likely contributors to diabetes risk in its myriad forms. Importantly, understanding the contribution of toxicants to diabetes risk as well as improved understanding of their mechanisms of action offer unique opportunities to modulate diabetes risk via targeted therapeutics or public policy interventions to reduce and remediate exposures.