Gestational diabetes (GDM), a pregnancy associated disease affecting about 7% of pregnancies worldwide, is associated with an increased risk of type 2 diabetes and endothelial dysfunction in later life (Buchanan et al., 2005). Under physiological conditions, reactive oxygen species (ROS) serve as important signalling molecules (Autreaux et al., 2007), but an overproduction of ROS and/or impaired antioxidant gene expression will compromise cellular defences against oxidative stress (Gao & Mann, 2009). In the present study, we have examined the effects of advanced glycation end-products on expression of endothelial nitric oxide synthase (eNOS) and heme oxygenase-1 (HO-1), an antioxidant enzyme, regulated by the redox sensitive transcription factor NF-E2-related factor 2 (Nrf2) (Siow et al., 1999), in human umbilical vein endothelial cells (HUVEC) isolated from normal and GDM pregnancies. HUVEC were cultured in M199 containing 20% FCS, and prior to experiments were deprived of serum (1% FCS) for 4 h and then challenged for 3-12h with AGE modified recombinant human serum albumin (AGE-HSA, 25-200µg/mL) or HSA. AGE-HSA (25 and 50µg/mL) increased eNOS expression 1.5-fold (arbitrary density: 25µg/mL: 0.37 ± 0.05 vs 0.61 ± 0.06, 50µg/mL: 0.36 ± 0.17 vs 0.62 ± 0.08, means ± S.E., n=3) in normal HUVEC (Fig. 1A). Notably, eNOS expression was similar in AGE-HSA or HSA-treated cells from GDM pregnancies. Although AGE-HSA also increased HO-1 expression after 6 h in normal HUVEC (Fig. 1B), HO-1 protein levels were not increased in endothelial cells from GDM pregnancies. As GDM is associated with impaired endothelial function, our findings provide insight into the molecular mechanisms underlying altered redox signalling in gestational diabetes.