This review puts forward the plausible glucose-lowering mechanism of dopamine receptor agonists, however more studies are needed to clarify the specific actions of central dopamine and prolactin and dopaminergic signaling in insulin-sensitive tissues which would identify potential therapeutic strategies for the treatment of metabolic disorders including type 2 diabetes and metabolic syndrome and even Parkinson’s disease. This evidence concerns the gene INS and type 2 diabetes mellitus.