Sitagliptin phosphate is a highly selective, orally active dipeptidyl peptidase-4 (DPP-4) inhibitor designed to enhance the body's natural glycemic response. It works by competitively inhibiting the DPP-4 enzyme, which is responsible for breaking down the active incretin hormones GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). By prolonging incretin lifetime, it naturally boosts glucose-dependent insulin secretion from beta-cells while suppressing inappropriate glucagon release from alpha-cells.