Fig. 5

Piperine improved oral glucose intolerance and insulin sensitivity detected by OGTT, hyperglycemic clamp experiment and ITT, respectively. a Plasma glucose levels were measured during an OGTT. b Area under the curve (AUC) in OGTT. c Glucose infusion rate in the hyperglycemic clamp experiment. d Plasma glucose levels were measured in ITT. e Percentage decrease of blood glucose at 40 min in ITT. Data are expressed as mean ± SD, n = 6–8. ^##p < 0.01, ^###p < 0.01 vs. Normal group; *p < 0.05, **p < 0.01,***p < 0.001 vs. Model group