Serum active GLP-1 level and oral glucose tolerance test in LETO and OLETF. a Serum level of the active form glucagon-like peptide (GLP-1) in OLETF treated with the vehicle or vildagliptin. Values in 4 of 5 samples from the vehicle-treated group were under the detection limit (<2.0 pmol/L) of the assay. Blood glucose (b) and serum insulin (c) during an oral glucose tolerance test (2 g glucose per kg body weight) in LETO (triangle) and OLETF treated with the vehicle (closed circle) or vildagliptin (open circle). *p < 0.05 vs. LETO and #p < 0.05 vs OLETF vehicle at each time point. N = 5 in each group. Vilda vildagliptin.