Insulin response to glucose challenge, chronic study. At 112 weeks, an intraperitoneal glucose tolerance test was performed in each group of mice (n = 6 per group). A: Insulin levels. B: GIR. Data are shown in means ± SEM. CR versus Reg, *P < 0.01, **P < 0.01; CR versus CR-high, §P < 0.05, §§P < 0.01.