INS and obesity due to melanocortin 4 receptor deficiency: Furthermore, compelling evidence is emerging for the role of persistent organic pollutants (POPs), such as polychlorinated biphenyls, dioxins, and pesticides, in chronic diseases such as type 2 diabetes [72–75] by impacting beta-cell function [72], insulin signaling and secretion [73], and mitochondrial function [74], as well as in the development of obesity by influencing adipocyte differentiation and neural circuits that control eating behavior (these toxicants have also thus been termed “obesogens”) [76].