The diabetic drug Sitagliptin (STG) is a hypoglycemic drug of the dipeptidyl peptidase-4(DPP-4) inhibitor. The new therapeutic action by DPP-4 inhibitors depends on the decrease of the glucagon levels and stimulates glucose-dependent insulin release. This is done through inhibition of the inactivation of incretins, particularly glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP), thereby improving glycemic control. Quantification Assay of STG in pharmaceutical preparations is one of the researchers' interests because of its importance in the manufacturing of drugs, quality control of the dosage forms, and the accuracy in determining the dose. However, in biological fluids, determination of the drugs is of greater importance, as monitoring the drug, studying its pharmacokinetics, bioavailability, potency, the chemical and biological actions of the drugs and their metabolites in the body. This is a review of STG, its properties, action, and methods of determination.