KDR and diabetes mellitus: VEGF and VEGFR protein expression levels were markedly up-regulated in the DM group compared with that in the NC group (VEGF: 0.51 ± 0.07 vs. 0.23 ± 0.11, p < 0.05; VEGFR: 0.79 ± 0.42 vs. 0.34 ± 0.08, p < 0.05, respectively).