Retatrutide vs Ozempic: T2D Phase 2 Cross-Trial Evidence (vs SUSTAIN-7)

This cross-trial comparison sits in Weight Loss Rankings' living editorial database — 350+ research articles and 200+ clinically-verified GLP-1 telehealth providers, sourced only from primary FDA labels, ClinicalTrials.gov registrations, and peer-reviewed PubMed literature.

The honest answer: Ozempic (semaglutide) is FDA-approved for type 2 diabetes since December 2017 and is widely available today. Retatrutide is investigational — no phase 3 T2D trial has been reported yet (TRIUMPH-2 is ongoing). Numbers below are an indirect cross-trial comparison between the Rosenstock 2023 phase 2 retatrutide T2D trial and the SUSTAIN semaglutide phase 3 program, not a head-to-head.

At a glance

• Retatrutide HbA1c at 24 wk (phase 2 T2D): −2.02% at 12 mg dose vs −1.41% on dulaglutide 1.5 mg and −0.01% on placebo (Rosenstock 2023, n=281).^[1]
• Ozempic HbA1c at 40 wk (SUSTAIN-7): −1.5% at 0.5 mg and −1.8% at 1.0 mg vs dulaglutide −1.1% / −1.4% (Pratley 2018, n=1,201).^[5]
• Weight change at 36 wk (retatrutide phase 2): −16.94% body weight at 12 mg vs −3.00% placebo and −2.02% dulaglutide.^[1]
• Weight change at 40 wk (Ozempic SUSTAIN-7): −4.6 kg at 0.5 mg and −6.5 kg at 1.0 mg vs dulaglutide −2.3 kg / −3.0 kg.^[5]
• Mechanism: retatrutide is a triple GIP + GLP-1 + glucagon receptor agonist; Ozempic is a GLP-1 receptor agonist only.
• Approval: Ozempic FDA-approved Dec 5 2017 (ApplNo 209637); retatrutide pre-approval everywhere worldwide as of mid-2026.^[8]
• Cardiovascular evidence: Ozempic has SUSTAIN-6 (3,297 T2D, NEJM 2016) confirming non-inferiority + reduced MACE; retatrutide's analogous CVOT is not yet designed for the T2D population.^[7]

Approval status — Ozempic FDA-approved 2017 for T2D, retatrutide investigational

Ozempic (semaglutide subcutaneous, Novo Nordisk) is FDA- approved for adults with type 2 diabetes mellitus as an adjunct to diet and exercise to improve glycemic control, and to reduce the risk of major adverse cardiovascular events (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke) in adults with type 2 diabetes and established cardiovascular disease. The original FDA approval date is December 5, 2017 (Application Number 209637); the current prescribing information lives on the DailyMed Ozempic SetID and reflects all post-approval label expansions.^[8][9]

Ozempic and Wegovy are the same molecule (semaglutide) at different doses with different indications: Ozempic is approved for T2D at weekly doses of 0.25 / 0.5 / 1.0 / 2.0 mg, while Wegovy is approved for chronic weight management at weekly doses up to 2.4 mg. For a patient with type 2 diabetes seeking an FDA-approved GLP-1 receptor agonist, Ozempic is the labeled product; Wegovy is the labeled product when the goal is weight loss in adults with obesity (BMI ≥ 30) or overweight (BMI ≥ 27) with at least one weight-related comorbidity. This article focuses on the T2D comparison.

Retatrutide (Eli Lilly, code LY3437943) is investigational. It has no FDA approval, no European Medicines Agency approval, and no approval in any jurisdiction worldwide as of May 2026. The TRIUMPH-2 phase 3 T2D pivotal trial (NCT05929079) has an estimated completion of May 2026 per ClinicalTrials.gov but has not been reported as of writing.^[10] The only retatrutide T2D efficacy data currently available is the Rosenstock 2023 phase 2 trial described below. Retatrutide is not eligible for legal 503A pharmacy compounding (not on the FDA bulk-substance list, not a discontinued FDA-approved drug); see our retatrutide sourcing / regulatory analysis for the legal detail.

HbA1c reduction — cross-trial comparison

The cleanest available comparison is the Rosenstock 2023 phase 2 retatrutide T2D trial (PMID 37385280) read against the SUSTAIN semaglutide phase 3 program. The retatrutide trial used dulaglutide 1.5 mg as the active comparator (not semaglutide), so the cross-trial bridge to Ozempic runs through SUSTAIN-7 (semaglutide vs dulaglutide; Pratley 2018, PMID 29397376).

• Retatrutide 12 mg — 24-wk HbA1c: −2.02% (least-squares mean change from baseline) vs −1.41% on dulaglutide 1.5 mg and −0.01% on placebo. Retatrutide 8 mg slow-escalation was −1.99%; 8 mg fast-escalation was −1.88%. Significantly greater than dulaglutide at the 8 mg slow (P=0.0019) and 12 mg (P=0.0002) doses.^[1]
• Ozempic 1.0 mg — 40-wk HbA1c (SUSTAIN-7): −1.8% vs dulaglutide 1.5 mg −1.4% (estimated treatment difference −0.41 pp; P<0.0001).^[5]
• Ozempic 0.5 mg — 40-wk HbA1c (SUSTAIN-7): −1.5% vs dulaglutide 0.75 mg −1.1% (ETD −0.40 pp; P<0.0001).^[5]

The headline difference, taken at face value: retatrutide 12 mg produced about 0.2 percentage points more HbA1c reduction than Ozempic 1.0 mg at the highest tested dose (−2.02% vs −1.8%). The differential is small but consistent in direction with what would be expected from a triple-agonist mechanism layering glucagon-receptor signaling on the GLP-1 backbone.

Both molecules also produced meaningful HbA1c reductions against placebo in monotherapy: Ozempic in SUSTAIN-1 (Sorli 2017, PMID 28110911) and in SUSTAIN-2 vs sitagliptin (Ahrén 2017, PMID 28385659), and in SUSTAIN-8 vs canagliflozin (Lingvay 2019, PMID 31540867). Retatrutide's only T2D data point is the Rosenstock 2023 phase 2.^[3][4][6]

Weight loss — cross-trial comparison

Weight loss is where the magnitude gap widens. Both trials are in patients with type 2 diabetes (not obesity), but the designs and time points are different.

• Retatrutide 12 mg — 36-wk body weight: −16.94% mean change from baseline vs −3.00% placebo and −2.02% dulaglutide 1.5 mg. All retatrutide doses ≥4 mg significantly greater than dulaglutide (P<0.0001).^[1]
• Retatrutide 8 mg — 36-wk body weight: −16.81% (slow escalation) / −16.34% (fast escalation).^[1]
• Ozempic 1.0 mg — 40-wk weight (SUSTAIN-7): −6.5 kg vs dulaglutide 1.5 mg −3.0 kg (P<0.0001). At baseline body weight ~95 kg this is roughly −6.8% mean change.^[5]
• Ozempic 0.5 mg — 40-wk weight (SUSTAIN-7): −4.6 kg vs dulaglutide 0.75 mg −2.3 kg (P<0.0001), roughly −4.8% mean change.^[5]

On the closest available cross-trial comparison, retatrutide 12 mg at 36 weeks produced roughly −17% mean body weight change in T2D, while Ozempic 1.0 mg at 40 weeks in T2D produced roughly −7%. That is a ~10 percentage-point absolute weight-loss advantage for retatrutide on indirect comparison — but the comparison should be read with all the cross-trial caveats below.

The Coskun 2025 body-composition substudy of the Rosenstock phase 2 trial (PMID 40609566) also reported DXA-measured fat mass changes: 23.2% fat-mass reduction at retatrutide 12 mg and 26.1% at 8 mg pooled vs 4.5% placebo, with the lean-mass-to-weight-loss ratio similar to other obesity therapies — reassuring against the hypothesis that the magnitude of weight loss reflects disproportionate lean-mass loss.^[2]

Mechanism — triple-class (GIP + GLP-1 + glucagon) vs GLP-1-only

Ozempic (semaglutide) is a single-receptor agonist at the GLP-1 receptor. GLP-1 receptor activation slows gastric emptying, increases glucose-dependent insulin secretion, suppresses glucagon at hyperglycemia, and reduces appetite through hypothalamic and brainstem signaling. Semaglutide is the most-studied GLP-1 receptor agonist in the modern era, with a phase 3 program (SUSTAIN 1–10) covering monotherapy, dual oral comparators, dual injectable comparators, insulin add-on, renal-impairment populations, and a cardiovascular outcomes trial.

Retatrutide adds two more receptor targets. It is a triple agonist at GIP, GLP-1, and glucagon receptors. The GIP component layers on additional weight-loss and glucose-dependent insulin effects similar to tirzepatide. The glucagon-receptor component is what differentiates retatrutide from anything currently FDA-approved: glucagon-receptor activation increases hepatic energy expenditure, promotes lipolysis, and accelerates hepatic fatty-acid oxidation. The net pharmacologic profile is greater weight loss and likely greater hepatic-fat reduction at the cost of a steeper tolerability curve and unique non-GI signals (the dysesthesia/paresthesia finding in the retatrutide obesity program; mild ALT elevations).

See our deep-dive on the retatrutide triple-agonist mechanism evidence for the receptor pharmacology and the structural-biology substrate.

Trial duration and populations differ — caveats

The cross-trial comparison sits on several caveats every reader should know before they treat the numbers as a clean head-to-head.

• Phase 2 vs phase 3. The retatrutide T2D number is a phase 2 trial (n=281) — exploratory by design. The Ozempic comparison number is from a phase 3 confirmatory trial (n=1,201). Phase 2 effect sizes often shrink in phase 3; the TRIUMPH-2 readout (expected late 2026) will settle whether the magnitude holds.^[1][10]
• Different active comparators. Rosenstock 2023 used dulaglutide 1.5 mg as the active arm; SUSTAIN-7 also used dulaglutide. The cross-trial bridge therefore reads "retatrutide vs dulaglutide vs semaglutide," adding an extra inferential step.
• Different durations. Retatrutide primary endpoint at 24 wk + body-weight endpoint at 36 wk; SUSTAIN-7 primary endpoint at 40 wk. GLP-1 weight-loss curves typically continue downward past 40 wk, so the retatrutide-vs-Ozempic weight-loss gap may narrow or widen at later time points.
• Different baseline populations. Rosenstock 2023 mean baseline HbA1c ~8.3% / mean BMI ~35; SUSTAIN-7 mean baseline HbA1c ~8.2% / mean BMI ~33. These are comparable but not identical.
• No randomized head-to-head exists. Until a direct retatrutide-vs-semaglutide T2D randomized trial is run, every claim here is indirect comparison.

Side-effect profile — cross-trial comparison

Both molecules show the GLP-1-class GI signal: nausea, vomiting, diarrhea, constipation. The magnitudes differ.

• Retatrutide phase 2 (pooled all doses): any GI adverse event in ~35% of retatrutide participants vs 13% placebo and 35% dulaglutide. Range across doses: 13% (at 0.5 mg) to 50% (at 8 mg fast-escalation).^[1]
• Ozempic SUSTAIN-7 (1.0 mg): nausea ~22%, diarrhea ~14%, vomiting ~11%, with overall GI-AE rate broadly comparable to dulaglutide.^[5]
• No severe hypoglycemia was reported in the retatrutide phase 2; the same finding is consistent across the SUSTAIN program with semaglutide monotherapy or background metformin — the hypoglycemia signal in either GLP-1 class is largely driven by concurrent insulin or sulfonylurea exposure.^[1][5]
• Dysesthesia / paresthesia. The retatrutide obesity program (TRIUMPH-1) flagged a ~12.5% paresthesia signal that does not appear in the SUSTAIN semaglutide program. The Rosenstock 2023 phase 2 T2D trial did not report this signal at comparable rates, but the trial was smaller and shorter than TRIUMPH-1.

Both molecules carry the standard GLP-1 class label warnings in the United States — pancreatitis (post-marketing, unconfirmed causal), gallbladder disease, acute kidney injury in the setting of severe GI volume loss, hypoglycemia when combined with insulin or sulfonylurea, retinopathy worsening in the SUSTAIN-6 dataset. See the GLP-1 side-effects Q&A hub and our GLP-1 side-effect timeline tool for the per-week onset pattern.

Cardiovascular outcomes — Ozempic has SUSTAIN-6, retatrutide CVOT pending

Ozempic has a completed cardiovascular outcomes trial: SUSTAIN-6 (Marso 2016, NEJM, PMID 27633186) randomized 3,297 adults with type 2 diabetes at high cardiovascular risk to semaglutide 0.5 mg or 1.0 mg vs placebo over 104 weeks. Primary outcome (composite of CV death, non-fatal MI, non-fatal stroke) occurred in 6.6% of semaglutide patients vs 8.9% on placebo (hazard ratio 0.74, 95% CI 0.58–0.95, P<0.001 for non-inferiority). The FDA label was subsequently updated to add the cardiovascular MACE-reduction indication for adults with T2D and established CV disease.^[7][9]

Retatrutide has no analogous T2D-population CVOT yet. TRIUMPH-3 (NCT05882045) is a CVOT but enrolls patients with obesity and established CV disease — not T2D primarily. Until a T2D-population CVOT reads out, retatrutide cannot claim an MACE-reduction benefit in T2D. This is a meaningful practical distinction: for a T2D patient with established atherosclerotic cardiovascular disease, Ozempic is the only molecule of the two with formal cardiovascular evidence.

Cost and availability today

Ozempic is commercially available across U.S. retail and specialty pharmacies. The Novo Nordisk list price for a monthly Ozempic pen is approximately $997/month before rebates or insurance, though most commercial-insurance patients pay $25–$200/month after manufacturer savings cards and prior-authorization approval. NovoCare and most major payers cover Ozempic for FDA-on-label T2D use; coverage for off-label weight loss is generally denied. Compounded semaglutide pricing in 2026 has narrowed substantially after FDA removed semaglutide from the drug shortages list in early 2025 — the compounded market is shrinking under enforcement pressure.

Retatrutide is not commercially available anywhere. There is no FDA-approved brand product, no list price, no pharmacy stocking it, and no legal 503A compounding pathway. The only legal access to retatrutide today is enrollment in an active TRIUMPH trial. Expected commercial launch is mid-to-late 2027 at the earliest, contingent on TRIUMPH-1 phase 3 obesity data supporting a Biologics License Application and on the FDA review cycle. See our retatrutide approval and access timeline for the current filing status.

When Ozempic makes more sense (FDA-approved, accessible, T2D-specific)

For most patients with type 2 diabetes today, Ozempic is the practical answer — not because the comparative pharmacology favors it, but because it is the molecule a prescriber can actually write today.

• You have T2D and need an FDA-approved option now. Ozempic is on-label, available at any U.S. retail pharmacy, has commercial-insurance coverage pathways, and is the standard of care for incretin-naive T2D patients who have not reached HbA1c target on metformin.
• You have established cardiovascular disease. SUSTAIN-6 supports an FDA-labeled MACE-reduction indication for Ozempic in adults with T2D and established CV disease. Retatrutide has no analogous T2D-population CVOT yet.^[7]
• You want predictable monthly costs. Even before insurance, Ozempic has a published list price and manufacturer savings programs. Retatrutide has neither.
• You want the longest post-marketing safety record. Semaglutide has been FDA-approved since 2017, with millions of patient-years of post-marketing exposure across Ozempic, Wegovy, and Rybelsus. Retatrutide's total clinical exposure is a few thousand trial patients over ~5 years.
• You have a prior intolerance to glucagon-receptor adjacent signals. The retatrutide phase 2 trial did not report comparable rates, but the obesity-program dysesthesia signal is a class-specific finding to watch as retatrutide T2D data matures.

The honest reverse case: if you have T2D plus class III obesity (BMI ≥ 40) and your treatment goal is the largest possible weight loss combined with HbA1c reduction, and you can wait for TRIUMPH-2 readout and FDA approval, then retatrutide will likely be the preferred option in 2027+ if the phase 2 magnitude holds in phase 3. Until then, Wegovy or Zepbound already offer ~15–21% TBWL with FDA approval today.

Practical takeaway

For type 2 diabetes in May 2026: Ozempic is FDA-approved, commercially available, supported by the SUSTAIN phase 3 program and a positive cardiovascular outcomes trial, and backed by ~9 years of post-marketing experience. Retatrutide's phase 2 T2D data are promising — −2.02% HbA1c and −16.94% body weight at 12 mg in a 281-patient phase 2 trial — but phase 3 (TRIUMPH-2) has not reported, no regulatory approval exists anywhere, and there is no legal access pathway outside of an active trial. A patient should not delay treatment in expectation of retatrutide; the GLP-1 / dual / triple class has FDA-approved options available today that produce clinically meaningful HbA1c and weight outcomes.

This article is a research review of published phase 2 and phase 3 data, not medical advice. Drug selection for type 2 diabetes is highly individualized — comorbidity profile (cardiovascular disease, chronic kidney disease, heart failure), baseline HbA1c, insulin therapy, and insurance coverage all matter. Discuss any treatment change with your prescribing clinician.

Related research

• Phase 2 retatrutide T2D deep-dive: Retatrutide for type 2 diabetes — phase 2 evidence review
• Retatrutide vs tirzepatide head-to-head: Retatrutide vs tirzepatide — TRIUMPH-1 vs SURMOUNT-1 evidence
• Tirzepatide vs Ozempic in T2D: Mounjaro vs Ozempic — SURPASS-2 head-to-head evidence
• Mechanism (triple agonist): Retatrutide as a triple GIP/GLP-1/glucagon agonist — evidence review