No impact of acute hyperglycaemia on arterial stiffness in the early and late follicular phases of the menstrual cycle in young females

New Findings: •What is the central question of this study? This is the first study to examine the impact of acute hyperglycaemia on arterial stiffness across the early and late follicular phases of the menstrual cycle. •What is the main finding and its importance? Central and peripheral arterial stiffness were not impacted by acute hyperglycaemia. This indicates that premenopausal women might experience protection against deleterious effects of acute hyperglycaemia, regardless of menstrual cycle phase. This research furthers our understanding of the interaction between nutrient intake, hormonal fluctuation and vascular function in premenopausal women. Abstract: Acute hyperglycaemia may result in transient increases in arterial stiffness. However, research in healthy premenopausal women is lacking, and the impact of menstrual phase [early follicular (EF; low oestrogen) and late follicular (LF; high oestrogen)] on vulnerability to acute hyperglycaemia-induced changes in arterial stiffness is unknown. We hypothesized that an acute hyperglycaemia-induced increase in arterial stiffness in the EF phase would be attenuated in the LF phase. Seventeen healthy, naturally menstruating women [21 ± 1 years of age (mean ± SD)] participated in three experimental visits. During two visits, in the EF and LF phase, arterial stiffness was assessed via central and peripheral (arm and leg) pulse wave velocity (PWV) before and 15, 45, 75 and 105 min after consuming an oral glucose challenge (75 g glucose in 300 ml of solution). Blood samples were taken to assess glucose, insulin, oestrogen and progesterone concentrations. During a third visit in the EF phase, participants ingested 300 ml of water as a time control for PWV. Despite significant increases in blood glucose and insulin (P < 0.001), both central and peripheral arm PWV remained unchanged across time and phase, indicating that neither acute hyperglycaemia nor menstrual phase had an impact on central or peripheral arm arterial stiffness. There was a small effect of phase for peripheral leg PWV, where PWV was lower in the LF phase (P = 0.04, Cohen's d = 0.39); however, and in contrast to recent results in young men, peripheral leg PWV was unaffected by hyperglycaemia. These results suggest that premenopausal women might experience protection from acute hyperglycaemia-induced increases in arterial stiffness.