Retatrutide: Phase 3 results and global availability timeline
Retatrutide (development code LY3437943) is an investigational peptide from Eli Lilly, designed as a once-weekly subcutaneous injection. It activates three hormone receptors at once: GIP, GLP-1, and glucagon. That makes it the first triple incretin agonist in late-stage development for obesity and type 2 diabetes.
On the metabolic side, the medical interest is clear. GLP-1 and GIP signalling reduces appetite, slows gastric emptying, and improves insulin response after meals, in the same family as semaglutide (GLP-1 only) and tirzepatide (GIP + GLP-1). Adding glucagon receptor activation targets energy expenditure and liver fat metabolism: the body burns more energy at rest and handles hepatic lipids differently. Researchers hope this third pathway can push weight loss and cardiometabolic markers beyond what dual agonists achieve, while staying within the incretin safety profile.
In a Phase 2 trial published in the New England Journal of Medicine (2023), adults with obesity and no diabetes lost up to 24.2% of body weight at 48 weeks on the 12 mg dose. That result justified the global Phase 3 TRIUMPH and TRANSCEND-T2D programmes. Retatrutide remains investigational: it is legally available only to participants in Lilly clinical trials, with no marketing authorisation anywhere yet.
Phase 3 results published so far
TRIUMPH-1 (obesity or overweight, no diabetes, at least one weight-related comorbidity) completed in 2026 with 2,339 participants over 80 weeks. Lilly reported in May 2026 that the 12 mg dose delivered an average 28.3% weight loss (~32 kg), with 45.3% of patients reaching at least 30% loss. At 4 mg, with a single dose-escalation step, average loss was 19.0%. In a pre-specified extension to 104 weeks among participants with baseline BMI ≥ 35, average loss reached 30.3% on 12 mg. Waist circumference, non-HDL cholesterol, triglycerides, systolic blood pressure, and hsCRP improved from baseline.
TRIUMPH-4 (obesity plus knee osteoarthritis, December 2025) showed up to 28.7% average weight loss at 68 weeks on the highest doses, with meaningful pain and function gains on the WOMAC scale.
TRANSCEND-T2D-1 (type 2 diabetes, March 2026) met its endpoints at 40 weeks in 1,290 adults: HbA1c fell by 1.7% to 1.9% across doses, with up to 15.3% weight loss.
Adverse events in TRIUMPH-1 followed the incretin pattern: nausea, diarrhoea, constipation, and vomiting, generally mild to moderate. Discontinuation due to adverse events was 4.1% (4 mg), 6.9% (9 mg), and 11.3% (12 mg), versus 4.9% on placebo. Dysesthesia and urinary tract infections were reported more often than with placebo; Lilly states most cases were mild and resolved during treatment. Full peer-reviewed publications and additional readouts (TRIUMPH-2, TRIUMPH-3) are expected through 2026.
Lilly is also running TRIUMPH-Outcomes (~10,000 participants) for cardiovascular and kidney events, with completion estimated around 2029, plus studies in sleep apnoea, liver disease, and chronic low back pain.
Global availability: where things stand
As of mid-2026, no regulator has approved retatrutide. Lilly has guided toward a US FDA submission in late 2026 once core TRIUMPH data are packaged. A standard FDA review typically takes about 10 months after filing, which points to a US decision in late 2027 or early 2028 if the timeline holds. These are projections, not confirmed launch dates.
United States (FDA). Investigational; first commercial access likely late 2027 to 2028 after a successful review.
European Union (EMA). Phase 3 sites in Germany, France, Spain, Italy, Poland, and others; no marketing application filed yet. Analysts project 2028 for obesity and 2029 for type 2 diabetes. National pricing and reimbursement still follow separately in each member state.
United Kingdom (MHRA). Investigational; projected 2028 for obesity.
Germany and other EU markets. Same EMA pathway; commercial access typically lags the US by roughly 12 to 18 months.
Japan (PMDA). Investigational; industry forecasts point to 2028 for type 2 diabetes first, with obesity potentially later depending on Japanese data requirements.
South Korea (MFDS). Investigational; major incretin launches often follow the US by 12 to 24 months (~2028 to 2029).
Canada and Australia. Trial sites active; projected 2028 range.
Brazil (Anvisa) and Mexico (COFEPRIS). Trial sites in both countries; regulators have warned that retatrutide sold online without authorisation is illegal and unverified. Legitimate pharmacy access would likely arrive after US approval, in the 2028 to 2029 window.
Until approval, the only regulated access is enrolment in a clinical trial. Search ClinicalTrials.gov or Lilly trial listings for open sites near you.
Gloe GLP-1 already supports Retatrutide alongside Mounjaro, Wegovy, Ozempic, and other GLP-1 medications in your dose planner. Whether you are on an approved drug today or following retatrutide trials from the sidelines, the app helps you log injections, titration steps, effects, weight, and stock with a reliable history for medical appointments. Your data stays on your device or in your private iCloud container.
Gloe GLP-1 does not provide medical advice. Always consult your healthcare professional for any treatment decision.
