LEP and diabetes mellitus: A new view of the nature and pathogenesis of DM-induced complications shared by many specialists nowadays has been prompted by the study of functional activity of hormonal signaling systems regulated by insulin, insulin-like growth factor-1 (IGF-1), and leptin, the principal players responsible for the development of DM and its central and peripheral complications, and by a wide spectrum of other hormones and neurotransmitters, including biogenic amines, purines, glutamate, peptide, and glycoprotein hormones controlling the fundamental cellular processes.