DRD2 and type 2 diabetes mellitus: Dopamine regulates whole-body metabolism by controlling food selection, food intake, satiety, and energy expenditure.27 Compelling evidence from humans and rodents demonstrates a marked reduction in dopamine concentration and turnover in the hypothalamus, as well as lower dopamine D2 receptor (D2R) density in the striatum in the presence of obesity and type 2 diabetes mellitus,27 suggesting a strong link between dopamine insufficiency and obesity-induced diabetes.