Impaired superficial femoral artery vasodilation and leg blood flow in young obese women following an oral glucose tolerance test

This study was designed to test the hypothesis that glucose ingestion following an overnight fast increases leg vascular conductance (LVCd) and superficial femoral artery (SFA) vasodilation in lean but not obese young women. Obese (23.5 ± 4.0 years, 84.7 ± 14.7 kg, 37.2% ± 6.4% fat; mean ± SD, n = 8) and lean (23.8 ± 2.4 years, 60.6 ± 4.0 kg, 22.3% ± 2.8% fat; n = 8) women arrived in the laboratory at 0830 h after a 12-h overnight fast for body composition (densitometry) assessment. Then, capillary blood glucose (BGlu), plasma insulin, heart rate, cardiac output, mean arterial pressure, leg blood flow (Doppler ultrasound), and LVCd were measured (after 15 min in the supine position), and at 30-min intervals for 2 h following glucose ingestion (75 g glucose load, 12.5% solution). Fasting BGlu concentration was not different between groups (obese = 5.1 ± 0.47 vs. lean = 4.9 ± 0.37 mmol·L(-1), p = 0.71) but 60, 90, and 120 min post ingestion BGlu was elevated (p ≤ 0.03) in the obese women. Insulin differences were not significant. Fasting LVCd was not different between groups (lean = 0.72 ± 0.49 vs. obese = 0.70 ± 0.19 mL·min(-1)·mm Hg(-1); p = 0.48); however, LVCd, as well as Δ in SFA diameter were significantly elevated (p ≤ 0.04) in the lean compared with the obese group at 60, 90, and 120 min postglucose ingestion (LVCd, peak lean = 1.4 ± 0.5 vs. peak obese = 0.8 ± 0.1 mL·min(-1)·mm Hg(-1); Δ in SFA, peak lean = 0.51 ± 0.30 vs. peak obese = 0.09 ± 0.45 mm). The reduced LVCd following glucose ingestion could contribute to impaired glucose tolerance. Further, the lack of SFA dilation may be evidence of impaired vascular insulin responsiveness in these obese young women.