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Retatrutide Clinical Results: Complete Data From Every Trial (2026)
Complete efficacy and safety data from all six completed retatrutide trials — Phase 2, TRIUMPH-1 through TRIUMPH-4, and TRANSCEND-T2D-1. Every number, every table, one place.
What's New: August 2026 Update
- TRIUMPH-2 confirmed (July 23, 2026): Obesity + type 2 diabetes trial, 1,152 patients — up to 20.8% weight loss and up to 1.6 percentage points HbA1c reduction at 80 weeks
- TRIUMPH-3 confirmed (July 23, 2026): Obesity + established cardiovascular disease trial, 1,949 patients — up to 22.6% weight loss at 80 weeks, plus significant improvements in triglycerides, blood pressure, and inflammatory markers
- All four core TRIUMPH trials are now complete — TRIUMPH-1, TRIUMPH-2, TRIUMPH-3, and TRIUMPH-4 have all reported positive topline results
- TRIUMPH-4 confirmed: 28.7% weight loss at 68 weeks in 445 participants — topline results announced December 2025
- TRIUMPH-1 confirmed (May 21, 2026): 28.3% average weight loss at 80 weeks in 2,339 patients — the pivotal general obesity trial met all primary and key secondary endpoints
- TRIUMPH-1 extension: In a prespecified 104-week extension, patients with BMI ≥35 reached 30.3% average weight loss — no plateau observed
- TRANSCEND-T2D-1 confirmed (topline March 2026, published June 2026): First dedicated Phase 3 diabetes trial — -2.0% HbA1c and 16.8% weight loss in 537 type 2 diabetes patients
- OSA data confirmed (ADA June 6, 2026): TRIUMPH-1's nested sleep apnea substudy showed 60.6% AHI reduction from a severe-OSA baseline of 58.6 events/hour
- Filing timeline updated: Eli Lilly will submit a Biologics License Application (BLA) — not an NDA, since retatrutide is a biologic — now expected Q1 2027 (shifted from the previously estimated Q4 2026)
Efficacy Summary Across All Completed Trials
Phase 2: The Foundation (2023)
The Phase 2 trial, published in the New England Journal of Medicine in June 2023, evaluated retatrutide in 338 adults with obesity (BMI ≥30) or overweight (BMI ≥27) with weight-related comorbidities. The study tested multiple doses (1mg, 4mg, 8mg, 12mg) against placebo over 48 weeks.
Phase 2 Weight Loss Results by Dose
The dose-response relationship was clear: higher doses produced progressively greater weight loss. The 12mg dose became the focus for Phase 3 development.
Phase 2 Responder Rates (12mg Dose)
- ≥15% weight loss: 83% of participants (vs. 9% placebo)
- ≥20% weight loss: 45% of participants (vs. 0% placebo)
- ≥30% weight loss: 6% of participants (vs. 0% placebo)
Phase 2 Safety Profile
Most GI side effects occurred during dose escalation (weeks 1–20) and improved thereafter. Discontinuation rate: 10.6% at the 12mg dose due to adverse events.
Phase 2 Metabolic Benefits
Beyond weight loss, retatrutide improved cardiometabolic markers:
- Blood pressure: Systolic BP decreased 7.4 mmHg (12mg dose)
- Triglycerides: Reduced 27% from baseline
- Fasting glucose: Decreased 13.8 mg/dL
- HbA1c: Reduced 0.4% (in participants without diabetes)
TRIUMPH-4: First Phase 3 Results (December 2025)
TRIUMPH-4 was the first Phase 3 trial to report. The trial enrolled 445 adults with obesity and moderate-to-severe knee osteoarthritis pain (without diabetes), randomized 1:1:1 to 9mg, 12mg, or placebo over 68 weeks.
TRIUMPH-4 Primary Results (68 Weeks, 12mg)
The 58.6% rate of ≥25% weight loss is notable — that threshold is broadly associated with bariatric surgery outcomes. More than 1 in 8 participants became completely free of knee pain by end of study.
TRIUMPH-4: Beyond Weight Loss
- Pain subscale (WOMAC): Improved 44 points vs. 13 points placebo
- Physical function: Improved 41 points vs. 12 points placebo
- 6-minute walk distance: Increased 63 meters (vs. 12 meters placebo)
TRIUMPH-4 Safety
Dysesthesia (tingling/altered sensation) appeared in 8.8% of participants at 9mg and 20.9% at 12mg, versus 0.7% placebo. This was the most distinctive safety finding from TRIUMPH-4. Discontinuation rate: 18.2% at 12mg due to adverse events.
TRIUMPH-1: The Pivotal General Obesity Trial (May 2026)
TRIUMPH-1 is the most important trial in the program for FDA purposes. Unlike TRIUMPH-4, which enrolled patients with knee osteoarthritis, TRIUMPH-1 enrolled 2,339 adults with general obesity (no required comorbidity) — the broad population retatrutide will be prescribed to after approval.
TRIUMPH-1 Primary Results (80 Weeks)
TRIUMPH-1 Dose Comparison (80 Weeks)
TRIUMPH-1: 104-Week Extension
In a prespecified extension for participants with BMI ≥35, average weight loss reached 30.3% (85.0 lbs) at 104 weeks. This confirms that weight loss does not plateau at 80 weeks. The 30.3% result crosses into territory previously associated only with bariatric surgery (typically 25–35% at 1–2 years).
TRIUMPH-1: Cardiometabolic Improvements (12mg, 80 weeks)
- Triglycerides: Reduced up to 41.0%
- Non-HDL cholesterol: Reduced up to 24.2%
- Systolic blood pressure: Reduced up to 12.3 mmHg
- Waist circumference: Reduced up to 24.1 cm
- hsCRP: Significant reduction (confirming systemic anti-inflammatory effect)
TRIUMPH-1 vs. TRIUMPH-4: Cross-Trial Comparison
Key takeaway: Nearly identical efficacy (28.7% vs. 28.3%) across different populations and durations. TRIUMPH-1's lower discontinuation rate (11.3% vs. 18.2%) and lower dysesthesia rate (12.5% vs. 20.9%) suggest better tolerability in a general obesity population without additional comorbidities. For a detailed comparison, see our TRIUMPH-1 vs. TRIUMPH-4 comparison.
TRIUMPH-2 and TRIUMPH-3 — covering more complex populations with diabetes and cardiovascular disease — showed lower efficacy (20.8% and 22.6% respectively), reflecting the impact of comorbidities rather than any inconsistency in the drug's effect. See the detailed breakdowns below.
TRIUMPH-2: Obesity with Type 2 Diabetes (July 2026)
TRIUMPH-2 enrolled 1,152 adults with obesity or overweight and type 2 diabetes, randomized 1:1:1:1 to retatrutide 4mg, 9mg, 12mg, or placebo over 80 weeks. Results reported July 23, 2026.
TRIUMPH-2 Results by Dose (80 Weeks)
Baseline HbA1c was 7.7%. Discontinuation due to adverse events ranged 3.8–11.6% across doses, compared with 4.9% for placebo — the exact rate per individual dose was not disclosed in topline results. Weight loss and glycemic improvement in this diabetes population were lower than in the non-diabetic TRIUMPH-1 population (28.3%) — a pattern also seen in TRANSCEND-T2D-1 (16.8%), Lilly's dedicated diabetes program described below. For more, see our Type 2 Diabetes guide.
TRIUMPH-3: Obesity with Established Cardiovascular Disease (July 2026)
TRIUMPH-3 enrolled 1,949 adults with severe obesity (BMI ≥35) and established cardiovascular disease, with or without type 2 diabetes, randomized 1:1:2 to retatrutide 9mg, 12mg, or placebo over 80 weeks. Results reported July 23, 2026.
TRIUMPH-3 Results (80 Weeks)
The MACE Data: What TRIUMPH-3 Actually Shows
TRIUMPH-3 also tracked major adverse cardiovascular events (MACE) — heart attack, stroke, and cardiovascular death:
- MACE-3 (3-component composite): hazard ratio 1.12 (95% CI 0.64–1.96) — 27 events on retatrutide vs. 23 on placebo
- MACE-5 (5-component composite): hazard ratio 0.82 (95% CI 0.55–1.22)
Neither result is statistically significant. The wide confidence intervals mean TRIUMPH-3 cannot confirm retatrutide reduces cardiovascular events, though it also shows no signal of increased risk. TRIUMPH-3 was not statistically powered to detect a MACE difference — that question is reserved for the dedicated TRIUMPH-Outcomes trial (~10,000 participants), not expected until 2028–2029. For the full breakdown, see our Cardiovascular Outcomes guide.
TRANSCEND-T2D-1: Diabetes-Specific Phase 3 Data (June 2026)
Separate from the TRIUMPH obesity program, Eli Lilly runs TRANSCEND-T2D — a dedicated Phase 3 program for type 2 diabetes. TRANSCEND-T2D-1 (NCT06354660) reported topline results on March 19, 2026, with full publication in The Lancet in June 2026.
The trial enrolled 537 adults with type 2 diabetes and inadequate glycemic control on diet and exercise alone. 85% were treatment-naive (no prior anti-diabetes medication). Baseline HbA1c was 7.9%, mean diabetes duration 2.5 years, mean BMI 35.8.
TRANSCEND-T2D-1 Results by Dose (40 Weeks)
The 16.8% weight loss in this population is substantially below TRIUMPH-1's 28.3% — a pattern consistent across the GLP-1 drug class, where type 2 diabetes reduces the magnitude of weight loss compared to non-diabetic obesity populations. No weight loss plateau was observed at 40 weeks. For the full breakdown, see our TRANSCEND-T2D-1 results guide.
TRIUMPH-1 OSA Substudy: Sleep Apnea Data (June 2026)
TRIUMPH-1's master protocol included a nested obstructive sleep apnea substudy for participants with confirmed moderate-to-severe OSA. Results were presented at the ADA 86th Scientific Sessions on June 6, 2026: retatrutide 12mg reduced the apnea-hypopnea index (AHI) by 60.6% — from a severe-OSA baseline of 58.6 events per hour to roughly 22.5 events per hour (mild-to-moderate range).
This is a clinically meaningful improvement, well above the 50% reduction threshold considered significant for sleep apnea treatment. For context, tirzepatide's SURMOUNT-OSA trial achieved 50.7–58.7% AHI reduction — retatrutide's 60.6% exceeds that range. For a detailed analysis, see our sleep apnea guide.
Safety Profile: All Completed Trials
Gastrointestinal Side Effects (12mg Dose)
GI side effect rates declined from Phase 2 to Phase 3 as dose escalation protocols improved. Phase 2 used more aggressive titration; TRIUMPH-4 and TRIUMPH-1 used gradual four-week dose escalation with better tolerability. For a complete breakdown, see our side effects guide.
Discontinuation Rates Due to Adverse Events (12mg)
TRIUMPH-1's 11.3% is a meaningful improvement over TRIUMPH-4's 18.2%. TRANSCEND-T2D-1's 5.1% is the lowest across all completed trials — likely reflecting the diabetes-specific population and shorter trial duration (40 vs. 68–80 weeks). TRIUMPH-2 reported a discontinuation range across doses (see its dedicated section above); TRIUMPH-3 did not disclose discontinuation rates in topline results.
Dysesthesia Across Trials
TRIUMPH-4 revealed dysesthesia (tingling, burning, or numbness) in 20.9% of participants at 12mg (8.8% at 9mg), versus 0.7% placebo. TRIUMPH-1 confirmed dysesthesia as a finding across the program, at 12.5% at 12mg — lower than TRIUMPH-4's rate. TRANSCEND-T2D-1 reported dysesthesia in 2.3–4.5% of participants. Most cases were mild to moderate and did not lead to discontinuation. For a detailed breakdown, see our dysesthesia guide.
Comparison to Other Obesity Medications
For the complete side-by-side comparison, see our retatrutide vs. tirzepatide vs. semaglutide guide. For month-by-month expectations of what weight loss looks like in practice, see our retatrutide weight loss timeline.
Sources
- Eli Lilly press release: Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials, delivering significant improvements in weight and A1C. July 23, 2026.
- PharmExec: Retatrutide Delivers Up to 22.6% Weight Loss in Two New Phase III Trials (per-dose breakdown for TRIUMPH-2 and TRIUMPH-3). July 2026.
- Eli Lilly press release: TRIUMPH-1 Phase 3 topline results. May 21, 2026.
- Eli Lilly. TRIUMPH-1 and TRANSCEND-T2D-1 full data. Presented at ADA 86th Scientific Sessions. June 6, 2026.
- Eli Lilly press release: TRIUMPH-4 Phase 3 topline results. December 11, 2025.
- Eli Lilly press release: TRANSCEND-T2D-1 Phase 3 topline results. March 19, 2026.
- Bajaj HS, et al. "Efficacy and safety of retatrutide (TRANSCEND-T2D-1)." The Lancet, 2026.
- Giblin K, Kaplan LM, Somers VK, et al. "Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis." Diabetes, Obesity and Metabolism, 2026;28(1):83-93.
- Jastreboff AM, et al. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial." NEJM, 2023;389:514–526.
- ClinicalTrials.gov: NCT05929066 (TRIUMPH-1), NCT05931367 (TRIUMPH-4), NCT06354660 (TRANSCEND-T2D-1).
Frequently Asked Questions
Six completed trials have now reported. Phase 2 (48 weeks, 12mg): 24.2% weight loss. TRIUMPH-4 Phase 3 (68 weeks, 12mg, 445 patients): 28.7% weight loss, with 58.6% achieving ≥25% — surgical-level outcomes. TRIUMPH-1 Phase 3 (80 weeks, 12mg, 2,339 patients): 28.3%, with 45.3% achieving ≥30%. A 104-week extension reached 30.3%. TRIUMPH-2 (80 weeks, 12mg, 1,152 patients with type 2 diabetes): 20.8% weight loss. TRIUMPH-3 (80 weeks, 12mg, 1,949 patients with cardiovascular disease): 22.6% weight loss. TRANSCEND-T2D-1 (40 weeks, 12mg, 537 T2D patients): 16.8% weight loss and -2.0% HbA1c. The highest results remain in the non-diabetic, non-cardiovascular-disease obesity trials (TRIUMPH-1 and TRIUMPH-4); TRIUMPH-2 and TRIUMPH-3 show somewhat lower efficacy in populations with added comorbidities.
Phase 2 (48 weeks, 12mg): 24.2% weight loss. TRIUMPH-4 Phase 3 (68 weeks, 12mg): 28.7%. TRIUMPH-1 Phase 3 (80 weeks, 12mg): 28.3%. The consistency between TRIUMPH-4 and TRIUMPH-1 — two different populations, different trial durations, nearly identical results — is strong evidence that retatrutide's efficacy is reproducible in general obesity populations. In populations with added comorbidities, results are lower: TRIUMPH-2 (obesity + diabetes) showed 20.8%, TRIUMPH-3 (obesity + cardiovascular disease) showed 22.6%, and TRANSCEND-T2D-1 (diabetes-specific, 40 weeks) showed 16.8% — all consistent with patterns seen across the GLP-1 drug class, where comorbidities reduce achievable weight loss.
Gastrointestinal effects are most common: nausea (42.4% in TRIUMPH-1 at 12mg), diarrhea (32.0%), vomiting (25.3%). These peak during dose escalation then improve. A unique finding is dysesthesia (tingling/altered sensation) in 20.9% at 12mg in TRIUMPH-4 and 12.5% in TRIUMPH-1. Discontinuation rates improved from TRIUMPH-4 (18.2%) to TRIUMPH-1 (11.3%) to TRANSCEND-T2D-1 (5.1%). TRIUMPH-2 reported discontinuation ranging 3.8–11.6% across doses. TRIUMPH-3 tracked cardiovascular events specifically (MACE), finding no statistically significant difference from placebo — neither harm nor confirmed benefit.
All four core TRIUMPH trials are now complete, with the final two — TRIUMPH-2 and TRIUMPH-3 — reporting July 23, 2026. Eli Lilly is preparing a Biologics License Application (BLA) — not an NDA, since retatrutide is a biologic — expected Q1 2027. FDA review takes 10–12 months under standard review, or approximately 6 months under priority review (if granted), projecting approval between Q3 2027 and Q1–Q2 2028, with commercial launch following 1–3 months later. Patients cannot access retatrutide outside of clinical trials until FDA approval.
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Disclaimer: This is not medical advice. Retatrutide is investigational and not FDA-approved. Consult your doctor. Full Medical Disclaimer.