Diabetes mellitus is now a global pandemic, with an estimated 463 million sufferers worldwide according to the International Diabetes Federation and is characterised by its chronic and complex nature requiring constant medical attention. Due to the varied and multifaceted pathophysiology, a number of different therapeutic options have been developed over the years for type 2 diabetes, including the inhibition of the enzyme dipeptidyl peptidase-4 (DPP-4). These DPP-4 inhibitors or gliptins are able to prevent the degradation of the incretin hormones, glucagon-like-peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which prolongs the glucose-mediated insulin secretory action of the incretins (i.e. the incretin effect). The five main gliptin available on the market include: sitagliptin, saxagliptin, vildagliptin, alogliptin and linagliptin, these are taken orally and have a glycaemic efficacy and safety characteristics which are akin to one another. They do however differ in terms of: potency, target selectivity, elimination half-life, oral bioavailability, protein binding, metabolism, excretion routes and dosage adjustment with regards to renal and hepatic insufficiency. DPP-4 inhibitors as a whole have been reported to be generally well tolerated and with a low risk of side effects.