The exact mechanisms underlying the elevated pre-intervention nucleotide levels in T1DM patients remain unknown and might be particularly defined by enhanced ATP release from endothelial cells in response to chronic hyperglycemia (Parodi et al., 2002); increased shear stress due to disturbed blood flow (Yegutkin et al., 2000, 2007); and/or by diminished activity of vascular endothelial NTPDase/CD39 (Robson et al., 2005). This evidence concerns the gene ENTPD1 and type 1 diabetes mellitus.