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Editorially reviewed · Last updated September 8, 2026 · How we review

Retatrutide for Type 2 Diabetes

Part of Retatrutide by Condition.

Retatrutide for Type 2 Diabetes

Retatrutide lowers A1C and body weight in type 2 diabetes trials, but it is not FDA approved. The Phase 3 TRANSCEND-T2D-1 trial, published in June 2026, randomized 537 adults whose diabetes was inadequately controlled with diet and exercise alone. At 40 weeks, the 12 mg group had an A1C reduction of 1.94 percentage points and 15.3% weight loss on the treatment-regimen estimand, versus 0.81 points and 2.6% with placebo.

The trial adds stronger evidence to the earlier Phase 2 study described below. It does not establish that retatrutide can replace insulin or that it is superior to an approved diabetes medicine. Retatrutide activates GLP-1, GIP, and glucagon receptors; each contributes to its pharmacological rationale.

Phase 2 Trial in Type 2 Diabetes

Published in The Lancet in 2023 (Rosenstock et al., NCT04867785), this was a 36-week, randomized, double-blind, placebo-controlled and active-comparator-controlled trial.

Study design

  • 281 participants with type 2 diabetes
  • 36 weeks of treatment
  • Doses tested: 0.5mg, 4mg (two titration schedules), 8mg (two titration schedules), 12mg
  • Comparators: Placebo and dulaglutide 1.5mg (an existing GLP-1 drug, marketed as Trulicity)
  • Conducted in the United States

HbA1c results at 24 weeks

GroupHbA1c change at 24 weeks (percentage points)
Placebo-0.01
Dulaglutide 1.5mg-1.41
Retatrutide 0.5mg-0.43
Retatrutide 4mg (2mg start)-1.39
Retatrutide 4mg (no escalation)-1.30
Retatrutide 8mg (2mg start)-1.99
Retatrutide 8mg (4mg start)-1.88
Retatrutide 12mg (2mg start)-2.02
These are the published 24-week primary endpoint results. Weight loss below is measured at 36 weeks; the two timepoints should not be combined into a single 36-week outcome. Rosenstock et al., The Lancet.

Weight loss results at 36 weeks

GroupWeight Change
Placebo-3.00%
Dulaglutide 1.5mg-2.02%
Retatrutide 4mg-7.92% to -10.37%
Retatrutide 8mg-16.34% to -16.81%
Retatrutide 12mg-16.94%

The -16.94% weight loss in a T2D population over 36 weeks is particularly notable. Patients with type 2 diabetes typically achieve less weight loss on GLP-1 drugs than patients without diabetes. This is a trial average, not an expected result for every person with diabetes.

How the Three Receptors Address Diabetes

Each of retatrutide's three receptor targets plays a distinct role in glucose metabolism:

GLP-1 (Glucagon-Like Peptide-1)

  • Stimulates glucose-dependent insulin secretion — insulin release depends on the glucose level; this is not a guarantee that hypoglycemia cannot occur
  • Suppresses glucagon secretion (from alpha cells) when blood sugar is high
  • Slows gastric emptying, reducing post-meal blood sugar spikes
  • Reduces appetite, contributing to weight loss

This is the mechanism behind semaglutide (Ozempic) and liraglutide (Victoza/Saxenda).

GIP (Glucose-Dependent Insulinotropic Polypeptide)

  • Enhances insulin secretion in a glucose-dependent manner, complementing GLP-1
  • May improve beta-cell function — the cells in the pancreas that produce insulin
  • Contributes to weight loss through additional appetite and metabolic effects

GIP is the second target in tirzepatide (Mounjaro), which achieved HbA1c reductions of up to -2.07% in the SURPASS-1 trial.

Glucagon Receptor

This is the most conceptually complex target for diabetes. Glucagon raises blood sugar — the opposite of what you want in a diabetes drug. However:

  • Glucagon promotes hepatic fatty acid oxidation and reduces liver fat, which improves hepatic insulin sensitivity — a core defect in T2D
  • Glucagon-related energy expenditure is part of the preclinical rationale; retatrutide studies in obese mice support this mechanism, but they do not quantify its contribution in people
  • The blood-sugar-raising effect of glucagon is counterbalanced by the strong insulin-stimulating effects of GLP-1 and GIP activation

The net clinical result was a reduction in average A1C. That supports glucose-lowering efficacy of the whole molecule; it does not isolate each receptor's contribution or rule out hyperglycemia in an individual.

How Retatrutide Compares to Existing Diabetes Drugs

The Phase 2 study included a direct comparator: dulaglutide 1.5mg. At 24 weeks, the retatrutide 12mg arm reduced A1C by 2.02 percentage points versus 1.41 with dulaglutide. At 36 weeks, weight loss was 16.94% versus 2.02%, respectively. These results apply to the studied doses and population. Published trial.
TRANSCEND-T2D-1 compared retatrutide with placebo. It did not compare it directly with semaglutide or tirzepatide, and separate trial averages cannot establish superiority. The dedicated TRANSCEND-T2D-1 page explains its dose arms and estimands.

The TRANSCEND Phase 3 Program

Eli Lilly is running the TRANSCEND Phase 3 program to evaluate retatrutide specifically for type 2 diabetes. This is a separate program from TRIUMPH (which focuses on obesity).

What we know

  • TRANSCEND-T2D-1 has reported: topline results in March 2026 and a peer-reviewed paper in June 2026.
  • It tested retatrutide as monotherapy over 40 weeks in adults inadequately controlled with diet and exercise alone.
  • Additional TRANSCEND studies address other treatment settings. Results from this trial should not be assumed to apply unchanged to insulin-treated patients.

Why a separate program matters

The FDA evaluates drugs by indication. A drug approved for obesity does not automatically have a diabetes indication — it requires separate clinical evidence. By running the TRANSCEND program in parallel with TRIUMPH, Lilly is positioning retatrutide for potential approval in both obesity and T2D, possibly with filings close in time.

What This Means for People with Type 2 Diabetes

Potential advantages of retatrutide over current options

The potential benefit is meaningful improvement in both glucose control and body weight. Evidence now includes a completed Phase 3 monotherapy trial as well as the earlier trial with a dulaglutide comparator. The liver-fat substudy addresses another metabolic outcome, but does not establish a treatment indication for MASH.

Important caveats

  • TRANSCEND-T2D-1 participants were not taking other diabetes medicines; it was not a trial of replacing insulin.
  • Gastrointestinal adverse events were common. The published trial reported no severe hypoglycemia, but that does not establish combination-treatment safety.
  • Long-term clinical outcomes and treatment choices still require further evidence.
  • Retatrutide is not an approved prescription treatment. Do not change existing diabetes medicines on the basis of these trial results.

Frequently Asked Questions

Is retatrutide approved for type 2 diabetes?

No. Retatrutide is not approved for any indication. TRANSCEND-T2D-1 has reported positive results and was published in June 2026. A positive trial does not establish an FDA approval date or authorize routine prescribing.

How does retatrutide compare to Ozempic for diabetes?

Retatrutide has not been directly compared with Ozempic in the trials summarized here. TRANSCEND-T2D-1 showed benefit against placebo, while the Phase 2 trial included dulaglutide. Comparing those results with a separate semaglutide trial cannot establish which medicine is better for an individual.

Would retatrutide replace insulin?

The published TRANSCEND-T2D-1 study does not answer that question: it enrolled adults whose diabetes was managed with diet and exercise alone, rather than testing withdrawal of insulin. Do not stop or reduce insulin because of these results. Any change requires the clinician managing your diabetes.

Can people with type 2 diabetes access retatrutide now?

Only through clinical trials. Trial eligibility and recruitment status vary; a completed trial such as TRANSCEND-T2D-1 is no longer enrolling. Search for trials at ClinicalTrials.gov or LillyTrialGuide.com.

Sources

Questions to ask your doctor

  • Is a GLP-1 medication an appropriate option for my condition specifically?
  • What does the evidence actually show for my condition, versus weight loss alone?
  • What are the alternatives, and how do they compare for me?
  • What risks or monitoring apply given my health history?
  • What results would be realistic, and over what timeframe?

How we keep this honest
What this is
Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
Regulatory status
Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
Our standard
Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
No commercial ties
We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.

Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Sources

Grounded in primary sources
NEJMThe LancetJAMAFDAClinicalTrials.gov

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