Increase in glucose metabolism in healthy humans administered with green tea. Oral glucose tolerance curves (OGTT, n = 22) and basal blood glucose levels (Basal, n = 25) before and 30, 60 and 120 min after administration with either a suspension of green tea powder (●) or hot water (○). All participants were fasted since the last supper before starting the experiment at 9:30 a.m. In the glucose tolerance test, 225 ml of Trelan-G75 containing 75 g glucose was perorally administered 10 min after drinking a suspension of green tea powder (1.5 g/150 ml hot water) or hot water (150 ml). Effect of green tea or hot water on basal blood glucose levels was examined without administrating Trelan-G75. Blood glucose levels (mg/dl) measured were averaged in each treatment group, and compared by cross-over test. Values represent the means ± S.E.M. *P < 0.05, **P < 0.01; significantly different from the vehicle control at each time-point, determined by one-way ANOVA, followed by Scheffé's test.