INTRODUCTION: Dipeptidyl peptidase (DPP)-4 inhibitors belong to one class of 
drugs that have been approved for treatment of type 2 diabetes (T2D) based on 
the glucose-lowering actions of the gastrointestinal hormone glucagon-like 
peptide (GLP)-1. Several different compounds are now available, and although 
their mechanism of action (inhibition of the catalytic activity of DPP-4) is the 
same, there are fundamental differences between them.
AREAS COVERED: The authors discuss the differences between different DPP-4 
inhibitors and review their therapeutic efficacy and key safety data. The 
literature covered includes original studies and meta-analyses identified in 
PubMed, recent abstracts presented at major diabetes scientific conferences, and 
clinical trials registered at ClinicalTrials.gov.
EXPERT OPINION: Although there are some differences in the pharmacokinetic and 
pharmacodynamic profiles of the different DPP-4 inhibitors, all are small orally 
active compounds with broadly similar HbA1c-lowering efficacy. They improve 
glycaemic control in T2D, without increasing the risk of hypoglycaemia or 
causing weight gain. They can be used as monotherapy or in combination with 
other anti-diabetic therapies, including insulin, regardless of renal or hepatic 
function, and are efficacious across the spectrum of patients with T2D, 
including those with long-standing disease duration. DPP-4 inhibitors may also 
have beneficial effects beyond glycaemic control, although this remains to be 
demonstrated in purpose-designed clinical trials.