Oral glucose tolerance test-induced increases in femoral blood flow are absent in nonobese females with polycystic ovary syndrome

The oral glucose tolerance test (OGTT) promotes transient increases in peripheral blood flow via humoral mechanisms, including insulin. Polycystic ovary syndrome (PCOS) is associated with insulin resistance and vascular dysfunction, even in nonobese females. We therefore tested the hypothesis that OGTT-stimulated increases in femoral blood flow (FBF) would be impaired in females with PCOS. In the overnight postabsorptive state, plasma glucose, insulin, and FBF (duplex ultrasound and superficial femoral artery) were measured pre-OGTT and at 0, 15, 30, 60, 90, and 120 min following a 75-g glucose bolus. We recruited females with PCOS [<i>n</i> = 10, age: 27 ± 5 yr, body mass index (BMI): 23.8 ± 3.1 kg/m²] and age- and BMI-matched females without PCOS (CTRL; <i>n</i> = 10, age: 27 ± 4 yr, BMI: 23.7 ± 2.0 kg/m²). Pre-OGTT glucose concentrations were not different between PCOS and CTRL (4.7 ± 0.4 vs. 4.7 ± 0.4 mmol/L, <i>P</i> = 0.74), nor were insulin concentrations (41.7 ± 12.0 vs. 32.4 ± 11.2 pmol/L, <i>P</i> = 0.11). However, OGTT glucose area under the curve (AUC; 938 ± 124 vs. 762 ± 113 mmol/L × 120 min, <i>P</i> = 0.01) and insulin AUC (45,121 ± 16,204 vs. 27,079 ± 11,527 pmol/L × 120 min, <i>P</i> = 0.01) were higher in PCOS than CTRL. Pre-OGTT, FBF was not different between PCOS and CTRL (211 ± 50 vs. 210 ± 44 mL/min, <i>P</i> = 0.95). FBF increased across all time points postbolus in CTRL but remained unchanged in PCOS (OGTT × group, <i>P</i> < 0.01). Indeed, FBF was lower in PCOS than CTRL at 30 (224 ± 33 vs. 277 ± 48 mL/min, <i>P</i> = 0.01), 60 (227 ± 37 vs. 305 ± 48 mL/min, <i>P</i> < 0.01), 90 (217 ± 45 vs. 308 ± 64 mL/min, <i>P</i> < 0.01), and 120 min (205 ± 47 vs. 258 ± 55 mL/min, <i>P</i> = 0.04) postbolus. In sum, nonobese females with PCOS demonstrated a complete absence of OGTT-stimulated increases in peripheral artery blood flow, suggesting that PCOS is associated with profound vascular dysfunction following acute hyperglycemia.<b>NEW & NOTEWORTHY</b> To the best of our knowledge, this is the first study to demonstrate that nonobese females with polycystic ovary syndrome (PCOS) do not exhibit oral glucose tolerance test-induced increases in peripheral blood flow, unlike healthy controls. These findings highlight the peripheral vasculature as a critical and overlooked component of cardiometabolic dysfunction in PCOS, even in the absence of obesity and other cardiometabolic risk factors (e.g., hypertension and diabetes).