Oxidative stress contributes to reductions in microvascular endothelial- and nitric oxide-dependent dilation in women with a history of gestational diabetes.

Women with a history of gestational diabetes mellitus (GDM) are twice as likely to develop cardiovascular disease (CVD) and ∼7 times as likely to develop type 2 diabetes as their age-matched counterparts. However, the mechanism(s) mediating these associations remain unclear. We hypothesized that endothelium- and (nitric oxide) NO-dependent dilation would be attenuated through oxidant stress mechanisms in the microvasculature of women with a history of GDM compared with control women with a history of uncomplicated pregnancy (HC). Ten HC (35 ± 4 yr) and 10 GDM (34 ± 4 yr) underwent a standard local heating protocol (42°C; 0.1°C·s-1). Two intradermal microdialysis fibers were placed in the ventral forearm for local delivery of lactated Ringer's (control) or 5 mM l-ascorbate. After full expression of the local heating response, 15 mM NG-nitro-l-arginine methyl ester (NO synthase inhibition) was perfused. Red cell flux was measured continuously by laser-Doppler flowmetry, and cutaneous vascular conductance (CVC = flux/MAP) was standardized to maximum (% CVCmax; 28 mM SNP + 43°C). Urine albumin:creatinine ratio (ACR) was measured. GDM had attenuated endothelium-dependent (GDM: 67 ± 7 vs. HC: 90 ± 4% CVCmax; P < 0.001) and NO-dependent (GDM: 54 ± 7 vs. HC: 71 ± 3% CVCmax; P = 0.001) dilation at the control site and tended to have higher urine ACR (P = 0.06). Both endothelium-dependent (R2 = 0.53, P = 0.02) and NO-dependent (R2 = 0.56, P = 0.01) dilation were related to urine ACR in GDM. l-ascorbate perfusion improved endothelium-dependent (82 ± 5% CVCmax; P = 0.03 vs. control) and NO-dependent (68 ± 5% CVCmax; P = 0.02 vs. control) dilation in GDM but had no effect in HC (P > 0.05). Otherwise healthy women with a history of GDM have attenuated microvascular endothelial function and this dysfunction is mediated, in part, by oxidative stress.NEW & NOTEWORTHY Women who have gestational diabetes during pregnancy are at greater risk for cardiovascular disease and type 2 diabetes in the decade following pregnancy. However, the mechanisms mediating this increased risk are unclear. Herein, we demonstrate that microvascular dysfunction, mediated by increase in oxidative stress, persists after pregnancy in women who had gestational diabetes, despite the remission of glucose tolerance.