The A₁ adenosine receptors (A₁AR), belonging to the rhodopsin-like superfamily of the G-protein-coupled receptors (GPCRs), may regulate many various cellular processes in cardiovascular, renal, and central nervous systems. In addition, since A(1)AR possesses antilipolytic properties, numerous A₁AR agonists and antagonists have been developed, but only some of them with the most promising selective properties in vitro have been advanced to animal studies and clinical trials. In this review, we have summarized the studies on the utility of A₁AR selective agonists and antagonists in the regulation of lipid and carbohydrate metabolism and their potential therapeutic applications in diabetes.