In type 2 diabetes mellitus (T2DM), glycaemic control is often difficult to maintain and current treatments can produce adverse effects. The incretin-based therapies—dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 (GLP-1) agonists—improve glycaemic control when added to conventional therapies and are well tolerated, with a low incidence of hypoglycaemia. In addition, the GLP-1 agonists reduce body weight and systolic blood pressure and improve surrogates of β-cell function. Incretin-based therapies may be appropriate for selected patients with T2DM when first-line therapy does not maintain glycaemic control, particularly where weight gain or hypoglycaemia are a concern. Copyright ©2009 John Wiley & Sons.