Oral glucose tolerance test-induced increases in femoral blood flow are absent in non-obese 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 non-obese 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 post-absorptive state, plasma glucose, insulin, and FBF (duplex ultrasound, superficial femoral artery) were measured pre-OGTT and at 0, 15, 30, 60, 90, 120-min following a 75-g glucose bolus. We recruited females with PCOS (n=10, age: 27±5yr, body mass index (BMI): 23.8±3.1kg/m2), and age- and BMI-matched females without PCOS (CTRL; n=10, age: 27±4yr, BMI: 23.7±2.0kg/m2). Pre-OGTT glucose concentrations were not different between PCOS and CTRL (4.7±0.4 vs 4.7±0.4mmol/L, P=0.74), nor were insulin concentrations (41.7±12.0 vs 32.4±11.2pmol/L, P=0.11). However, OGTT glucose area under the curve (AUC; 938±124 vs 762±113mmol/Lx120min, P=0.01) and insulin AUC (45121±16204 vs 27079±11527pmol/Lx120min, P=0.01) were higher in PCOS than CTRL. Pre-OGTT, FBF was not different between PCOS and CTRL (211±50 vs 210±44mL/min, P=0.95). FBF increased across all time points post-bolus in CTRL but remained unchanged in PCOS (OGTT x group, P<0.01). Indeed, FBF was lower in PCOS than CTRL at 30- (224±33 vs 277±48mL/min, P=0.01), 60- (227±37 vs 305±48mL/min, P<0.01), 90- (217±45 vs 308±64mL/min, P<0.01), and 120-min (205±47 vs 258±55mL/min, P=0.04) post-bolus. In sum, non-obese 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.