Retatrutide — questions, answered plainly.

Retatrutide (development code LY3437943) is a single lipidated peptide engineered to activate three metabolic receptors simultaneously: GIP, GLP-1, and glucagon. It is investigational — not FDA-approved at the time of writing.

Triple agonist means a single molecule activates three distinct receptors. Retatrutide acts at the GIP, GLP-1, and glucagon receptors. GIP + GLP-1 activity is shared with tirzepatide; the additional glucagon-receptor activity is associated with energy-expenditure effects in metabolic research.

Jastreboff et al. 2023 (NEJM, PMID 37366315; n=338) reported dose-dependent mean body weight reductions of 17.1%–24.2% with retatrutide 4–12 mg versus 2.1% with placebo over 48 weeks in adults with obesity or overweight plus comorbidity.

Rosenstock et al. 2023 (Lancet, PMID 37385280; n=281) reported dose-dependent HbA1c reductions up to 2.02% and body-weight reductions up to 16.94% with retatrutide 4–12 mg over 36 weeks in adults with type 2 diabetes.

No. Retatrutide is investigational. Phase III trials (the TRIUMPH programme for obesity and TRIUMPH-OUTCOMES for cardiovascular outcomes) are ongoing at the time of writing.

All published efficacy data are from Phase 2 trials with limited duration (36–48 weeks). Long-term safety, cardiovascular outcomes, and direct head-to-head comparison with tirzepatide or semaglutide have not been established. Clinical interpretation requires forthcoming Phase III data.