NOS3 and type 2 diabetes mellitus: In T2D, endothelial progenitor cells synthesize less NO because of the damaged eNOS-caveolin-1 complex (Aicher et al., 2003[4]; Cao et al., 2012[22]) that is associated with increased serum levels of Dickkopf-1, which is an inhibitor of osteoblast differentiation (Lattanzio et al., 2014[90]).