Yes, in the trial data so far, retatrutide has lowered blood sugar in people with type 2 diabetes. In a Phase III type 2 diabetes trial, Inside Precision Medicine reports the highest average A1C drop was 2.0 percentage points over 40 weeks. As of October 2026, Inside Precision Medicine reports retatrutide is not yet FDA-approved, so there is no approved label for it yet.
This page sticks to blood sugar and the safety questions that come with it.
How much does retatrutide lower blood sugar?
Eli Lilly is developing retatrutide, which acts on three hormone receptors. The 2023 review in Expert Opinion on Investigational Drugs says it stimulates GLP-1, GIP and glucagon receptors. The diabetes results below come from adults with type 2 diabetes.
A1C is the test that shows your average blood sugar over about three months. The NIDDK's diabetes page explains how the test works.
| Study | Who was in it | What it measured | Reported result |
|---|---|---|---|
| Phase III type 2 diabetes trial, as reported by Inside Precision Medicine | Adults with type 2 diabetes | A1C and body weight over 40 weeks | Highest average A1C drop 2.0 percentage points; highest average weight drop 16.8% |
| Phase 2 obesity trial, in the 2023 review | Adults with obesity | Weight change at 24 weeks | Weight fell by 7.2% to about 18% as the dose rose from the lowest to the highest tested |
| 2026 analysis of two Phase 2 trials, Study 1 | Adults with obesity or overweight and type 2 diabetes, over 36 weeks | Blood fat and inflammation markers, not blood sugar | Non-HDL cholesterol fell by up to 21.0%; apolipoprotein B fell 21.4% |
How does retatrutide lower blood sugar?
Harvard Health describes how GLP-1 drugs in general work. They increase insulin release in response to meals and lower glucagon, a hormone that raises blood sugar. Harvard Health notes they lower blood sugar only when it is high.
Retatrutide adds glucagon receptor action to that. Inside Precision Medicine describes the hoped-for benefit of the glucagon part as greater energy expenditure, alongside GLP-1's effect of making people eat less and reducing A1C. For how blood sugar, weight and digestion connect, read our page on weight loss, blood sugar and digestion.
Does retatrutide increase heart rate?
Yes. In the 2023 review's Phase 2 data, retatrutide increased heart rate by up to 6.7 beats per minute. The review's expert opinion section says this may be detrimental and could offset some of the benefits of weight loss.
| Side effect | What the source reports | Source |
|---|---|---|
| Nausea, vomiting, diarrhea | The most frequent adverse events in the Phase 2 obesity trial of retatrutide | 2023 review |
| Nausea, vomiting, diarrhea, constipation | The most common side effects of GLP-1 drugs in general | National Academy of Medicine GLP-1 basics |
| Dizziness, headache, increased heart rate | Other side effects of GLP-1 drugs in general | National Academy of Medicine |
| Pancreas, stomach, intestine, gallbladder or kidney problems | Less common with GLP-1 drugs in general | National Academy of Medicine |
| Low blood sugar | Usually not on its own; can happen when GLP-1 medicines are taken with insulin or a sulphonylurea | Diabetes UK's GLP-1 guide |
Is retatrutide bad for the kidneys?
The kidney study described here was done in mice, so it does not show what retatrutide does to human kidneys. Ask your diabetes team, and check the trial records for human kidney findings.
The 2024 study in db/db mice with diabetic kidney disease, published in a PubMed-indexed journal, found retatrutide improved kidney function and reduced weight more than liraglutide and tirzepatide did. The same study found retatrutide did not outperform those two on lowering blood glucose, where tirzepatide did better. Treat the mouse results as early, since they do not directly tell you what happens in people.
Diabetes UK says GLP-1 medicines can be prescribed to reduce the risk of major cardiovascular events such as heart attack or stroke in people with cardiovascular disease and obesity or overweight. It also says kidney disease stage can decide whether a GLP-1 is suitable or whether the dose needs to change.
What else did the studies measure?
A 2026 analysis in Diabetes, Obesity & Metabolism looked at heart-risk markers in adults with obesity or overweight, with or without type 2 diabetes. It was a post hoc analysis, meaning it looked at data after the trials. In the group with type 2 diabetes (Study 1, 36 weeks), retatrutide was compared with dulaglutide and placebo, and the 2026 heart-risk marker analysis reports reductions in several blood fat markers. These are not blood sugar measures.
Is retatrutide approved for type 2 diabetes?
No, not yet. As of October 2026, Inside Precision Medicine reports retatrutide is not yet FDA-approved, though Eli Lilly is developing it. With no approved label, there is no official dosing or pricing information to check yet.
You may see compounded GLP-1 products online. The National Academy of Medicine says the FDA has not assessed compounded GLP-1 versions for safety, effectiveness or quality, and that some may be fraudulent. It also passes on the FDA's advice to fill prescriptions at a state-licensed pharmacy.
Can retatrutide be used for type 1 diabetes?
This page covers type 2 diabetes. Type 1 is a different disease. The NIDDK's type 1 diabetes page says that if you have type 1 diabetes, you need to take insulin to stay alive. Diabetes UK says GLP-1s are not licensed to treat type 1 diabetes and are not a replacement for insulin.
What is still not known?
- Long-term results. The National Academy of Medicine says researchers keep monitoring muscle mass, bone health and mental well-being as GLP-1 drugs are used for longer periods.
- Head-to-head results. The 2023 review said comparator studies against semaglutide or tirzepatide were needed.
- Exact Phase III figures. The A1C and weight numbers above reach you through a news report. Check the full trial record for exact figures.
What should you ask your diabetes team before considering retatrutide?
Bring these questions to your diabetes team before you consider retatrutide or any GLP-1 medicine:
- Insulin or sulphonylurea use. Diabetes UK says low blood sugar can happen when GLP-1 medicines are taken with these, and that your team may adjust those doses.
- Kidney stage. Diabetes UK says kidney stage can decide whether a GLP-1 is suitable or whether the dose changes.
- Pancreatitis, pregnancy and breastfeeding. Diabetes UK lists a history of pancreatitis, pregnancy and breastfeeding among reasons a GLP-1 may not suit you.
- Approval status. Ask whether a product is FDA-approved and what its label says, once one is available.
If you are also looking at other ways to support blood sugar, our page on magnesium for type 2 diabetes covers the research, types and safety questions for that option.
By SterlingMedicalCenter.org Editorial Team