Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, C98
Glycaemic response and insulin sensitivity during the menstrual cycle in women
S. E. Hillier1, M. C. Venables1,2, R. Craven1
1. Functional Food Centre, Oxford Brookes University, Oxford, United Kingdom. 2. Human Health and Performance Research Group, Oxford Brookes University, Oxford, United Kingdom.
There is conflicting evidence concerning the influence of fluctuations in estradiol and progesterone during the menstrual cycle on glycaemic response and insulin sensitivity (Bingley et al. 2008; Yeung et al. 2010). One reason for this could be the failure to establish accurate menstrual phase definition by analysis of hormone concentrations. The aim of this study was to investigate glucose response to a 75g glucose load and insulin sensitivity at three set time points during the menstrual cycle. Venous blood samples for baseline measurements of estradiol and progesterone were collected every other week day from ten regularly menstruating women for one complete menstrual cycle (age 28 ± 1 yrs, weight 60.18 ± 8.24 kg and height 1.66 ± 0.07 m). An oral glucose tolerance test (OGTT, 75g glucose) was performed on three separate days during the next complete menstrual cycle. In the 24 hour period prior to each OGTT participants replicated their diet and avoided exercise, caffeine and alcohol. Venous blood samples were taken before each test session to confirm estradiol and progesterone concentrations. Capillary blood samples were taken at -5 and 0 minutes for fasting glucose and insulin concentrations, followed by the ingestion of 75g glucose dissolved in 250ml of water. Capillary blood samples were then taken every 15 minutes for the first hour and every 30 minutes for the following two hours (3 hours total). Average glucose and insulin area under the curve (AUC) was calculated following OGTT completion. In addition, insulin sensitivity was calculated by HOMA-IR (Matthews et al. 1985) and Matsuda (Matsuda and DeFronzo 1999) equations. Data is presented as means ± SD. Variables were analysed using one-way repeated measures ANOVA. Significance was accepted at the P<0.05 level. Hormone concentrations (estradiol and progesterone) differed significantly during one complete menstrual cycle (Table 1); however even with accurate menstrual phase definition there was no significant difference in glucose AUC, insulin AUC or insulin sensitivity between the three test sessions. This suggests that fluctuations in estradiol and progesterone during the menstrual cycle may not influence glucose or insulin response to a glucose load.
Where applicable, experiments conform with Society ethical requirements