Dicarbonyl glycation of RGD and GFOGER sites in type IV collagen has been associated with decreased angiogenesis. In this study, we investigated whether overexpression of glyoxalase 1 to decrease dicarbonyl glycation would prevent the angiogenesis deficit induced by hyperglycemia in vitro. Transfection of human microvascular endothelial cells resulted in a four-fold increase in glyoxalase 1 activity compared with controls. Incubation of human microvascular endothelial cells in model hyperglycemia produced a 32% decrease in formation of tube structures that was prevented by glyoxalase 1 overexpression. We conclude that increased protection against dicarbonyl glycation of endothelial cell protein protects hyperglycemia-induced angiogenesis deficit.