Skip to content
For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement.
AMIRAVOResearch Library

Semaglutide vs retatrutide

Semaglutide is an FDA-labeled GLP-1 receptor agonist, and retatrutide is an investigational agonist of the GIP, GLP-1 and glucagon receptors still described as under study in 2026 trial reports. 1,2 No trial comparing them directly was identified, so this page places their placebo-controlled obesity trials alongside each other while noting the differences in design. 3,4

Unbranded reference vial illustrating Semaglutide; not an actual product
Semaglutide
FDA-approved
Unbranded reference vial illustrating Retatrutide; not an actual product
Retatrutide
Investigational

Side by side

FieldSemaglutideRetatrutide
ClassGLP-1 receptor agonist 1GIP, GLP-1 and glucagon receptor agonist 4
Mechanism / receptorsSelective GLP-1 receptor activation; the label also states that semaglutide delays gastric emptying. 1Triple-receptor agonism; preclinical work in obese mice attributed part of the weight effect to glucagon-receptor-mediated energy expenditure. 5
OriginModified GLP-1 analogue, yeast-derived backbone, C18 fatty di-acid. 1Synthetic investigational peptide (LY3437943). 5
Half-lifeApproximately 1 week (per label). 1Approximately 6 days in a review of phase 1 and 2 data. 6
Highest trial phaseApproved; phase 3 (STEP program) 3Phase 3 (TRIUMPH and TRANSCEND programs) 4,7
FDA statusLabel (Wegovy) covers cardiovascular-event risk reduction, chronic weight management and noncirrhotic MASH (accelerated approval). 1Described as under investigation in 2026 reports; no FDA label was identified. 2
Published outcomes (weight)STEP 1, 68 weeks, no diabetes: -14.9% vs -2.4% with placebo. 3TRIUMPH-1, 80 weeks, no diabetes: -17.6%, -23.7%, -25.0% (4, 9, 12 mg) vs -3.9% with placebo. 4
Studies in type 2 diabetesWegovy label, Study 3 (type 2 diabetes with obesity or overweight, 68 weeks): -9.6% vs -3.4% with placebo. 1TRIUMPH-2 (80 weeks): -11.9%, -16.8%, -18.8% (4, 9, 12 mg) vs -5.1% with placebo. 2
Safety signalsBoxed thyroid C-cell tumor warning (rodent data); pancreatitis and gallbladder disease warnings. 1Gastrointestinal events; heart-rate increases in phase 2; hypotension and dysesthesia in TRIUMPH-2. 2,8
Evidence levelRegulatory and randomized phase 3 human evidence 1,3Randomized phase 2 and 3 human trials; no label identified 4,8

Semaglutide: what the data says

STEP 1 enrolled 1,961 adults with obesity or overweight and without diabetes, randomized 2:1 to semaglutide 2.4 mg once weekly or placebo for 68 weeks. 3 Mean weight change was -14.9% versus -2.4% with placebo, and weight reductions of at least 15% were reported for 50.5% of the semaglutide group versus 4.9% of the placebo group. 3

The Wegovy label reports a 68-week trial in adults with type 2 diabetes and obesity or overweight in which mean body weight change was -9.6% with semaglutide versus -3.4% with placebo. 1 Its pooled adverse-reaction table lists nausea in 44% versus 16% with placebo. 1

Retatrutide: what the data says

TRIUMPH-1 randomized 2,339 adults with obesity and without diabetes to retatrutide 4, 9 or 12 mg or placebo once weekly for 80 weeks; mean weight change was -17.6%, -23.7% and -25.0% versus -3.9% with placebo. 4 In subgroups, the trial reported changes in knee-osteoarthritis pain scores and in apnea-hypopnea index in participants with obstructive sleep apnea. 4

TRIUMPH-2 enrolled 1,152 adults with obesity and type 2 diabetes; weight change at week 80 was -11.9%, -16.8% and -18.8% versus -5.1% with placebo, with diarrhea in 27% to 34% of retatrutide groups versus 13% with placebo. 2 A phase 3 monotherapy trial in type 2 diabetes (TRANSCEND-T2D-1) reported HbA1c changes at 40 weeks and bodyweight changes of -11.5% to -15.3% versus -2.6% with placebo. 7

Key research differences

  • Receptor targets: semaglutide is a selective GLP-1 receptor agonist, while retatrutide is a GIP, GLP-1 and glucagon receptor agonist. 1,4
  • STEP 1 ran for 68 weeks and TRIUMPH-1 for 80 weeks, with different placebo-group changes (-2.4% and -3.9%), so the percentages from the two trials are not directly comparable. 3,4
  • In adults with type 2 diabetes, the Wegovy label's study reported -9.6% versus -3.4% with placebo at week 68, whereas TRIUMPH-2 reported -11.9% to -18.8% versus -5.1% at week 80. 1,2
  • Regulatory position differs: semaglutide has FDA-labeled indications including cardiovascular-event risk reduction and MASH, while retatrutide has no label identified in the sources reviewed. 1,2
  • Retatrutide trials have reported dose-dependent heart-rate increases (phase 2) and hypotension and dysesthesia signals (phase 3), which differ from the label-listed warnings for semaglutide such as pancreatitis and gallbladder disease. 1,2,8

Where the evidence is limited

No head-to-head trial of semaglutide and retatrutide was identified. 3,4 Cardiovascular-outcome and long-term safety data for retatrutide were not found in the sources reviewed, whereas the semaglutide label includes a cardiovascular-event indication. 1,4 The trials also differ in duration, doses and population, which limits cross-trial interpretation. 3,4

Frequently asked questions

Has retatrutide been compared with semaglutide head-to-head?
No such trial was identified in the sources reviewed; each has been studied against placebo in separate trials. 3,4
Which receptors do the two molecules act on?
Semaglutide is described on its label as selectively activating the GLP-1 receptor, and retatrutide is described in trial reports as an agonist of the GIP, GLP-1 and glucagon receptors. 1,4
Is retatrutide an FDA-approved medicine?
The 2026 trial reports reviewed describe retatrutide as under investigation, and no FDA label was identified. 2,7
Do both have reported gastrointestinal effects?
Yes. Nausea and diarrhea were the most common adverse events with semaglutide in STEP 1, and gastrointestinal events were the most common adverse events in the retatrutide trials. 2,3,4

References

  1. WEGOVY (semaglutide) injection, prescribing information FDA label (DailyMed). 2026
  2. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2) Lancet. 2026
  3. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) N Engl J Med. 2021
  4. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1) N Engl J Med. 2026
  5. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept Cell Metab. 2022
  6. The First Triple Agonist for Antiobesity: Retatrutide Cardiol Rev. 2024
  7. Efficacy and safety of retatrutide in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1) Lancet. 2026
  8. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial N Engl J Med. 2023

For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. This page compares published research and is not medical advice or a recommendation.