In trials, retatrutide improved the two basic markers of kidney function. In people with obesity, the 12 mg dose lowered the amount of protein in the urine by 31.5 percent compared with placebo and raised the kidney filtration rate by 8.5 ml/min. In people with type 2 diabetes, the amount of protein in the urine fell by 37.0 percent. Below we explain what these figures mean and describe the trials that are under way.
Which markers show how the kidneys work?
In trials, kidney function is described by two markers. The first is eGFR, the estimated glomerular filtration rate, which shows how much blood the kidneys clean in a minute. A higher result means better kidney function.
The second marker is UACR, the albumin to creatinine ratio in the urine. It shows how much protein leaks into the urine, which is one of the first signs of strain on the kidneys. Here a lower result is better. Obesity and type 2 diabetes increase the risk of kidney disease, which is why both markers are measured in trials of medicines for these conditions.
What did the analysis of phase 2 trials show?
The analysis covered two phase 2 trials: 281 people with type 2 diabetes and 338 people with overweight or obesity without diabetes. Participants received retatrutide at doses from 0.5 to 12 mg or placebo. The results were published in 2025 in Kidney International Reports.
| Result compared with placebo | Retatrutide 8 mg | Retatrutide 12 mg |
|---|---|---|
| Protein in urine, obesity, after 48 weeks | down 28.0 percent | down 31.5 percent |
| Kidney filtration, obesity, after 48 weeks | up 5.3 ml/min | up 8.5 ml/min |
| Protein in urine, type 2 diabetes, after 36 weeks | not reported | down 37.0 percent |
In people with diabetes, kidney filtration did not change compared with placebo. The rise in filtration in people with obesity was confirmed by two different ways of calculating it. One is based on creatinine, and the other on cystatin C, another blood protein.
How should these results be read?
Most participants had normal kidney function at the start. Average filtration was about 90 ml/min, and protein in the urine was usually within the normal range. The authors note that, as a result, the absolute fall in urine protein was small.
The results therefore show a direction, not proof of kidney protection in kidney disease. Answers to that second question are expected from trials in people with diagnosed chronic kidney disease. We describe them below.
Where might the benefit for the kidneys come from?
Retatrutide acts at once on several factors that strain the kidneys. It lowers body weight, blood pressure and blood sugar. Each of these factors on its own is linked to the risk of kidney disease.
- Body weight: in the phase 2 trial the 12 mg dose lowered it by 24.2 percent after 48 weeks.
- Blood pressure: a 2026 meta-analysis found an average fall in systolic pressure of 6.79 mm Hg.
- Blood sugar: in TRANSCEND-T2D-1 glycated haemoglobin fell by 1.94 points at 12 mg.
Which part of the effect comes from which factor is not known. A 2026 study in mice also tested a direct effect on kidney fibrosis. Retatrutide acted most strongly of the three medicines compared, but results in animals need to be confirmed in humans.
Which kidney trials are under way?
The most important is the TRANSCEND-CKD trial in people with chronic kidney disease and overweight or obesity. It included 146 people with an average age of 65.1 years and an average measured filtration of 49.3 ml/min. Participants receive retatrutide up to 12 mg or placebo, and the main result is the change in filtration after 24 weeks.
Filtration in this trial is measured more precisely than usual, by giving a tracer and measuring how it is cleared from the blood. Magnetic resonance imaging will also show blood flow in the kidneys and the fat around them. The results are meant to support the large TRIUMPH-Outcomes trial, which tests the effect of retatrutide on the heart and kidneys.
Why precise measurement matters here can be seen from the baseline data. Filtration calculated from creatinine averaged 64.2 ml/min, and from cystatin C 49.6 ml/min, about the same as the tracer measurement. Creatinine depends on muscle mass, so with a large drop in weight it can give a misleading picture. Among the participants, 37.7 percent had type 2 diabetes, and 21.8 percent took SGLT-2 inhibitors.
How does it compare with semaglutide?
Semaglutide already has the results of a large kidney trial in people with diabetes and kidney disease, the FLOW trial. On that basis the medicine Ozempic received a kidney indication in 2025. This is described in the guide semaglutide and tirzepatide beyond weight loss.
There are no such results for retatrutide yet, because the kidney trials are still under way. The phase 2 data, however, point in the same direction. The effect of retatrutide on blood sugar is described in the guide on retatrutide and type 2 diabetes, and on the liver in the guide on retatrutide and fatty liver.
Where to buy retatrutide?
The shop offers retatrutide in three versions from three makers. Retatrutide 20 mg Bio-Peptide costs 200 EUR and is in stock. Retatrutide 20 mg Genheal costs 200 EUR and is available on backorder. Retatrutide 40 mg Nouveaux in a pen costs 350 EUR, which is 8.75 EUR per milligram instead of 10 EUR.
Retatrutide is not an approved medicine, and the products in the shop are material for laboratory research. Kidney disease is treated by a doctor, and no research material replaces that. All variants are listed on the retatrutide page.
Frequently asked questions
Does retatrutide harm the kidneys?
In phase 2 trials kidney markers improved. Protein in the urine fell by 31.5 percent in people with obesity and by 37.0 percent in people with diabetes at 12 mg.
Does retatrutide improve kidney filtration?
In people with obesity the 12 mg dose raised filtration by 8.5 ml/min compared with placebo after 48 weeks. In people with diabetes filtration did not change.
What is UACR?
It is the albumin to creatinine ratio in the urine. It shows how much protein leaks into the urine and is one of the first signs of strain on the kidneys.
Has retatrutide been tested in people with kidney disease?
The TRANSCEND-CKD trial is under way in 146 people with chronic kidney disease and obesity. The main result is the change in filtration after 24 weeks.
Where does the effect on the kidneys come from?
Retatrutide lowers body weight, blood pressure and blood sugar, and each of these factors strains the kidneys. The share of each has not yet been separated.
Sources
- Heerspink HJL, Lu Z, Du Y et al. The Effect of Retatrutide on Kidney Parameters in Participants With Type 2 Diabetes Mellitus and/or Obesity. Kidney International Reports, 2025, 10(6): 1980-1992. https://doi.org/10.1016/j.ekir.2025.03.049
- Heerspink HJL, van Raalte DH, Bjornstad P et al. Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide in patients with chronic kidney disease. Nephrology Dialysis Transplantation, 2026, 41(6): 1058-1068. https://doi.org/10.1093/ndt/gfaf230
- Jastreboff AM, Kaplan LM, Frías JP et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. New England Journal of Medicine, 2023, 389(6): 514-526. https://doi.org/10.1056/NEJMoa2301972
- Simental-Mendía LE, Barragán-Zúñiga LJ, Reyes-Avitia V. Effect of Retatrutide, a Novel Triple Receptor Agonist, on Blood Pressure and Lipid Levels: A Systematic Review and Meta-analysis of Randomized Controlled Trials. High Blood Pressure and Cardiovascular Prevention, 2026, 33(5): 503-516. https://doi.org/10.1007/s40292-026-00812-6
- Bajaj HS, Welch M, Shah P et al. Efficacy and safety of retatrutide in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1). The Lancet, 2026, 407(10546): 2402-2413. https://doi.org/10.1016/S0140-6736(26)00967-0
- Ding M, Li X, Wei Y et al. Comparative effects of semaglutide tirzepatide and retatrutide on renal fibrosis in UUO and aged mice. iScience, 2026, 29(9): 117174. https://doi.org/10.1016/j.isci.2026.117174