Retatrutide Research Peptides

Retatrutide, development code LY3437943, is an investigational synthetic peptide that activates GIP, GLP-1 and glucagon receptors. It is being studied in obesity, type 2 diabetes and related metabolic complications.

In the peer-reviewed Phase 2 obesity trial, mean body-weight change at 48 weeks ranged from -8.7% in the 1 mg group to -24.2% in the 12 mg group, compared with -2.1% with placebo. Later Phase 3 obesity results have reported larger reductions in some groups, but several of those figures were still company topline results rather than peer-reviewed primary publications when checked.

No. Retatrutide and tirzepatide are different molecules. Retatrutide is a GIP, GLP-1 and glucagon receptor agonist, whereas tirzepatide targets GIP and GLP-1 receptors. A direct Phase 3 comparison is underway, but no results were posted when checked.

Gastrointestinal events such as nausea, diarrhoea, constipation and vomiting have been common in the clinical programme. The Phase 2 obesity study also reported a dose-dependent rise in heart rate, and company Phase 3 reporting has described dysaesthesia. The long-term and rare-event safety profile is still developing.

A Phase 1b human study reported an elimination half-life of approximately six days. That finding supported the once-weekly schedules used in later clinical trials.

Human trials have used several investigational regimens, including target doses from 1 mg to 12 mg once weekly depending on the trial, often with protocol-defined escalation for higher target doses. These are research protocols, not personal dosing instructions.

Yes. A Phase 2 trial and the peer-reviewed Phase 3 TRANSCEND-T2D-1 trial both studied retatrutide in adults with type 2 diabetes and reported improvements in glycaemic measures and body weight.

A 98-person Phase 2a substudy in participants with metabolic dysfunction-associated steatotic liver disease and at least 10% liver fat reported large relative reductions in liver fat at 24 weeks. It was a substudy of the obesity programme, so it should not be treated as definitive evidence for all liver outcomes.

The major human studies and Phase 3 programme reviewed here use subcutaneous retatrutide. This research did not identify a validated oral retatrutide clinical programme or an authorised oral retatrutide product.

No. The MHRA stated in July 2026 that retatrutide has not been authorised for use in the UK.

A Phase 3 head-to-head trial, TRIUMPH-5, is comparing retatrutide with tirzepatide in adults with obesity. It was active but not recruiting and had no posted results when checked on 19 September 2026.