In the pathogenesis and progression of PD and DM, insulin and dopamine are regulated mutually, and hypoinsulinemia induced by streptozotocin can reduce the levels of dopamine transporter (DAT) and tyrosine hydroxylase (TH) transcription in the substantia nigra pars compacta (Lima et al., 2014). This evidence concerns the gene SLC6A3 and Hypoinsulinemia.