Effects of Vildagliptin on DPP-4 activity and active GLP-1 levels. A:Vildagliptin increases active plasma GLP-1 levels after 12 weeks treatment. B: Vildagliptin reduces DPP-4 activity after 12 weeks treatment.Data are presented as means ± SEM. N = 8-10 for all groups. *P < 0.05 vs. sham group; $P < 0.05 vs. MI group.