Unraveling the Science of Incretin Biology

Plasma concentrations of (A) glucose and (B) insulin during the intravenous administration of different doses (0.4, 0.8, and 1.2 pmol/kg per min of glucagon-like peptide 1 (GLP-1) (solid symbols) or placebo (open symbols) administered in the fasting state for 300 minutes in 12 patients with type 2 diabetes mellitus. At 60 minutes a mixed meal (1,050 kJ [250 kcal]) was served. Data are expressed as mean ± SEM. P values for each figure are as follows: (A) p = 0.01 for difference between the doses tested, p<0.001 for differences over time, and p<0.001 for differences due to the interaction of experiment and time; (B) p = 0.96 for difference between the doses tested, p<0.001 for differences over time, and p<0.001 for differences due to the interaction of experiment and time. *p<0.05) vs. placebo at individual time points. (Reprinted with permission from J Clin Endocrinol Metab) [46].

Structural features of (A) glucagon-like peptide–1 (GLP-1), (B) exenatide, (C) liraglutide, and dipeptidyl peptidase–4 (DPP-4) inhibitors (D) vildagliptin, (E) sitagliptin, and (F) saxagliptin. (Adapted with permission from Lancet.) [33].