Retatrutide lowered A1C more than placebo in a phase 2 trial of adults with type 2 diabetes. The Lancet report of that trial, published in 2023, says every retatrutide dose group except the lowest one did better than placebo on HbA1c. As of October 2026, the Lancet's 2026 phase 3 report describes retatrutide as “currently under investigation for the treatment of obesity, type 2 diabetes,” so it is still a study drug and not a finished diabetes medicine.
What did retatrutide do to A1C in the phase 2 trial?
The Lancet phase 2 trial enrolled adults aged 18 to 75 with type 2 diabetes, an HbA1c of 7.0% to 10.5% and a BMI of 25 to 50. Participants were on diet and exercise alone or on a stable dose of metformin. The trial ran for 36 weeks, and its primary endpoint was the change in HbA1c at 24 weeks. In total, 190 people received retatrutide, 45 received placebo and 46 received dulaglutide 1.5 mg.
The abstract reports that HbA1c reductions with retatrutide were “significantly greater” than placebo in every group except the 0.5 mg group (p<0ยท0001). Two higher-dose groups also beat dulaglutide 1.5 mg: the 8 mg slow-escalation group and the 12 mg escalation group. The authors describe the results as “clinically meaningful improvements in glycaemic control,” and say the findings were consistent at 36 weeks. The trial was funded by Eli Lilly and Company.
The abstract gives the group comparisons. For the exact A1C drop in each group, open the full paper. You can also read the who was in the retatrutide trial guide to see who took part.
What is the newest phase 3 A1C result for retatrutide?
Eli Lilly, the maker of retatrutide, reported topline results from its phase 3 TRANSCEND-T2D-1 trial in March 2026. In that company report, A1C fell by about 1.7 to 2.0 percentage points across doses over 40 weeks, in 537 adults with type 2 diabetes. Lilly also reported body weight reductions of roughly 11.5% to 16.8%. You can read more about who took part in the who was in the retatrutide Ozempic trial guide.
For comparison, the phase 2 Lancet trial reported A1C drops of up to 2.02 percentage points at 24 weeks in its highest-dose group, so the phase 3 range sits in the same zone. These phase 3 figures are the maker's own summary and have not yet appeared as a full paper that independent scientists have reviewed.
Ozempic is the brand name for semaglutide, a once-weekly injection for type 2 diabetes, according to Diabetes UK. A head-to-head comparison with Ozempic is still something to check in the full paper once it is published and peer reviewed.
Here is what is still unknown: the dose-by-dose detail, the full side-effect picture and how long the benefit lasts. Retatrutide is not approved, so these results do not change what you can get today. Before you change anything, ask your clinician how new diabetes data would fit your own plan.
What did the 2026 phase 3 trial find?
The TRIUMPH-2 phase 3 report enrolled adults with a BMI of 27 or higher and type 2 diabetes with an HbA1c of 6.5% to 10.5%. It ran at 92 centres and hospitals in eight countries. Its main focus was bodyweight. At week 80, the mean change was -11.9% with 4 mg, -16.8% with 9 mg, -18.8% with 12 mg and -5.1% with placebo. The abstract says treatment “was associated with improvements in glycaemic control,” and for the exact A1C change, read the full paper.
What does the A1C number mean, and what makes someone type 2 diabetic?
The NIDDK type 2 diabetes page says a health care professional can diagnose type 2 diabetes “based on blood tests.” The NIDDK type 1 diabetes page explains that “The A1C test shows your average blood glucose level over the past 3 months.” It also notes that blood glucose tests “don't show the type of diabetes you have.”
The 7.0% to 10.5% range above describes who could join the trial, not a diagnosis line. To learn what your own result means and what target fits you, ask your clinician.
Can people with type 1 diabetes or insulin resistance use retatrutide?
Both trial reports above enrolled people with type 2 diabetes. The NIDDK type 1 page says, “If you have type 1 diabetes, you need to take insulin to stay alive.” The Diabetes UK GLP-1 guide says “GLP-1s are not licensed to treat type 1 diabetes” and “GLP-1s are not a replacement for insulin, and their use in type 1 diabetes is still being studied.” Those statements are about GLP-1 medicines in general. Retatrutide also acts on the GLP-1 receptor, but it is a different drug with different targets.
Diabetes UK also notes that “hypos can happen when you take GLP-1 agonists with other diabetes medications such as insulin or a sulphonylurea.”
On insulin resistance, the phase 2 abstract names HbA1c and bodyweight as its endpoints. If insulin resistance is what you are tracking, ask your prescriber which test they use.
How does retatrutide work on blood sugar and weight?
The TRIUMPH-2 abstract describes retatrutide as “an agonist of GIP, GLP-1, and glucagon receptors.” If you saw the term “GLP-3,” the trial papers use the receptor names above instead.
For GLP-1 medicines in general, the National Academy of Medicine GLP-1 basics page says, “GLP-1s work by slowing stomach emptying, increasing feelings of fullness, and reducing appetite. They also help the pancreas release insulin when blood sugar levels are high.” Weight loss was a separate endpoint in the phase 2 trial, and it was reported alongside the A1C results.
What side effects did the trials report?
In the phase 2 trial, the abstract reports mild-to-moderate gastrointestinal side effects, which were nausea, diarrhoea, vomiting and constipation. It also says there were no reports of severe hypoglycaemia and no deaths during the study.
| Phase 2 group | Participants | Gastrointestinal side effects |
|---|---|---|
| Retatrutide, all groups | 190 | 67 (35%) |
| Placebo | 45 | 6 (13%) |
| Dulaglutide 1.5 mg | 46 | 16 (35%) |
The phase 3 TRIUMPH-2 abstract lists these side effects by dose.
| TRIUMPH-2 group | Diarrhoea | Nausea | Hypotension | Dysesthesia | Stopped due to side effect or death |
|---|---|---|---|---|---|
| 4 mg | 27% | 14% | 1% | 4% | 11 (4%) |
| 9 mg | 34% | 21% | 5% | 6% | 33 (12%) |
| 12 mg | 34% | 28% | 6% | 7% | 22 (8%) |
| Placebo | 13% | 8% | <1% | 1% | 14 (5%) |
The abstract says the investigator judged all deaths in the trial unrelated to the study drug. Both reports cover 36 to 80 weeks, so longer-term safety is still unknown.
Is retatrutide available, and is it safe to buy online?
Retatrutide is still under investigation, so it is not a standard diabetes treatment you can get from your clinician today. For the approval status and what it means for access, read is retatrutide fda approved, and for timing, see the retatrutide availability timeline.
If you come across retatrutide sold online, keep the National Academy of Medicine warning about compounded GLP-1 products in mind. That page says, “The US Food and Drug Administration (FDA) has not assessed these formulations for safety, effectiveness, or quality,” and that “some may be fraudulent.”
Before you talk to your clinician
Bring these questions to your next appointment:
- What does my latest A1C mean, and what target fits me?
- Is a clinical trial an option for me? The phase 2 Lancet abstract lists the registration number NCT04867785.
- Which test do you use to check insulin resistance, if that is my concern?
- Are there approved options for my type 2 diabetes that I should compare?
- Before changing any diabetes medicine, what should I check with you first?
By the New Life Wellness Guide Editorial Team