Tirzepatide (Mounjaro), a first-in-class dual incretin agonist of the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors, is approved for use as an adjunct to diet and exercise to improve glycaemic control in adults with type 2 diabetes mellitus (T2DM) in the USA, EU, Japan and other countries. It comes as single-dose prefilled pens and single-dose vials. In phase III SURPASS trials, once-weekly subcutaneous tirzepatide, as monotherapy or add-on-therapy to oral glucose-lowering medications and insulin, was superior to the GLP-1 receptor agonists (RAs) dulaglutide 0.75 mg and semaglutide 1 mg as well as basal and prandial insulin for glycaemic control and weight loss in adults with inadequately controlled T2DM. Tirzepatide was generally well tolerated, with a safety profile consistent with that of GLP-1 RAs. Tirzepatide was associated with a low risk of clinically significant or severe hypoglycaemia and no increased risk of major adverse cardiovascular events. Adverse events were mostly mild to moderate in severity, with the most common being gastrointestinal events including nausea, diarrhoea, decreased appetite and vomiting. In conclusion, tirzepatide is a valuable addition to the treatment options for T2DM.