In general, lipopolysaccharide-induced EIU causes significant vasodilation.26 It was previously demonstrated that diabetes reduced vein vasodilation in the retinas of rats with EIU, probably by the decreased expression of iNOS.27 This decreased expression of iNOS would also explain the suppressed leukocyte rolling and accumulation, because of its effect on the expression of P-selectin and ICAM-1.12–14 Our findings are consistent with these preceding reports. Here, NOS2 is linked to diabetes mellitus.