Diabetic kidney disease is a leading cause of end-stage kidney disease, with nearly half of all cases triggered by poorly controlled blood glucose. Now, researchers say, they have found a way to help people living with type 1 and type 2 diabetes stave off renal failure and improve their kidney function. This March 2026, kidney specialists reported in the New England Journal of Medicine that the drug Finerenone is safe and effective for type 1 diabetes.
Finerenone Reduced ACR Readings by 30%
In a randomized placebo controlled clinical trial, doctors pitted Finerenone against a placebo to see whether patients who took the drug showed fewer signs of kidney damage than participants who took the placebo. Over the course of the trial, consisting of 242 patients, participants who used Finerenone reduced the levels of protein in their urine by a third. Participants given the placebo reduced their protein levels by 12%.
Finerenone has already proved promising for people with type 2 diabetics. In 2020 members of the FIDELIO-DKD consortium announced the results of a long-term clinical trial in theNEJM. They showed that type 2 diabetics prescribed Finerenone were less likely to develop renal failure or die and had a 40% improvement in estimated glomerular filtration rate from baseline within two and a half years of beginning treatment.
Since then, it has continued to demonstrate encouraging results, with doctors reporting positive effects on other complications of diabetes, including reserved ejection fraction heart failure and liver disease. Given the success of the drug in type 2 diabetics, experts were keen to see if it would have similar success in people living with type 1 diabetes.
Finerenone and Type 1 Diabetes
Why would doctors need to test this again if they know it works for type 2 diabetics? Type 1 and type 2 diabetes have many aspects of their pathology in common, but the causes of these conditions are different. Type one diabetics have no ability to manufacture their own insulin. When a child or adult develops type 1 diabetes, they get a diagnosis relatively soon and doctors can monitor for complications caused by too much glucose in their blood, or too little glucose.
Type 2 diabetes is more complicated. This disorder occurs when a person’s body loses the ability to respond to insulin, and eventually they might lose the ability to even make insulin. As a result, it takes longer for folk to realize that something is wrong, and it can be difficult to know when the effects of high blood glucose levels started to impact their body.
In practical terms this means that type 2 diabetics and type 1 diabetics have different needs: a useful drug for type 2 diabetics might not be necessary at all for type 1 diabetics.
Putting Finerenone to the test
The FINE-One consortium of investigators is an international collaboration between nephrologists focused on figuring out whether Finerenone is a safe and effective drug for type 1 diabetics. This phase 3 clinical trial took place over six months in hospitals across Europe, the Americas and Australia and was a randomized, double-blind placebo-controlled experiment.
This experimental design is as good as it gets as far as ensuring that the results are down to the drug and not unintentional measurement biases or the placebo effect.
The aim of this trial was to test the drug on type 1 diabetics who already had chronic kidney disease to see whether it would improve their kidney function. They would recruit two very similar groups of type 1 diabetics showing signs of chronic kidney damage caused by their diabetes. One group would take Finerenone every day at the standard dose for six months. The other group would take a sham pill on an identical schedule. How would the two treatments compare?
What’s in Your Urine?
The researchers intended to measure kidney function at different points over the six months. This would allow them to see whether the drug was helping or hindering kidney function. They chose to use urinary albumin to creatinine ratio scores (ACR) as a proxy for organ function.
Why did they opt to track ACR? Normally, our kidneys can distinguish between creatinine proteins and albumin proteins. They save the albumin and get rid of creatinine. If you have a lot of albumin in your urine, it means your kidneys are not working very well. This is an easy way for doctors to see whether your kidneys are functioning well and allows them to watch and see if they get better or worse over time. It’s also an easy, noninvasive test – they just have to collect a urine sample.
The team planned to collect urine samples throughout the trial. At the beginning of the trial to show the starting point, or baseline ACR levels. The next after three months, then at the end of the drug course at six months and a final sample a month after ending treatment. These data points would help the research team to track changes in kidney function over time. It also meant that if anybody had an unexpected adverse reaction, they would catch it quickly and be able to pin down when it started.
At the end of the trial, the researchers would analyse the changes in ACR at each time point and overall to figure out: firstly, does Finerenone improve kidney function in type 1 diabetics? Secondly, does Finerenone work better than a placebo? Finally, is Finerenone safe for people with type 1 diabetes and existing chronic kidney disease?
Who’s Who?
The nephrologists used a statistical power calculation to determine out how many people they needed to recruit in order for the trial to be representative. When you have too few subjects in a trial, it can be difficult to draw conclusions if the chances of confounding factors skewing the results are high. They reasoned that they would need at least 100 people in each test condition to get a meaningful result either way. They screened over thousand patients to see who would be a good candidate for the trial, finally enlisting 242 willing volunteers.
The participants had an average age of 51 years, were around 35% female and had a racial breakdown of approximately 70% white, 5% Black, 4% other and 20% Asian. Importantly, none of them had a history of chronic kidney disease caused by something other than diabetes, and none had received a kidney transplant.
Only people with chronic kidney disease were asked to join the trial. They defined chronic kidney disease as an estimated glomerular filtration rate (e-GFR) of 25 to less than 90 ml per minute per 1.73 m2 of body surface area; a urinary albumin (mg) to creatinine (g) ratio (ACR) of between 200 mg/g and 5000 mg/g and at least three months history of proteinuria. To put this in perspective, a normal eGFR is around 90, and a normal ACR is less than 30 mg/g. Would Finerenone help people with Type 1 diabetes?
Where Did Patients Start?
The average ACR of the participants was more than 500 mg/g and the eGFR around 59. The average subject had been living with type 1 diabetes for over 30 years and around a third of them had a history of cardiovascular disease.
So we are starting with a group of people who already have chronic kidney disease, and have been accumulating damage for a long time. The nephrologists invited these people to take part rather than healthier volunteers because they wanted to find out whether Finerenone could not only slow the progression of kidney disease, but improve the prognosis of people who are already sick.
The participants were randomized into two closely matched groups, neither the doctors treating and monitoring the patients nor the participants were told which group they were in. The control group comprised 122 participants and the Finerenone group, 120. Doctors gave members of the Finerenone group either 10 mg (eGFR 25-60) or 20 mg (60 ml or more) of the drug in oral form every day. They gave the placebo group a daily identical looking sham treatment. At the end of the trial, eight of the Finerenone group and ten of the placebo group participants had dropped out, leaving 112 in the experimental group and 112 in the control group.
How Did They Measure Improvement?
The nephrologists measured every participant’s urinary albumin to creatinine ratio at the start of the trial, after three months, then six months and finally a month post treatment end. Nobody knew which patients got a placebo and got the drug until the very end of the trial when the researchers analysed the results.
The higher the ACR reading, the less well a person’s kidneys are working. In previous studies, doctors have seen that Finerenone reduces type 2 diabetics’ ACR readings. This means they find an improvement in kidney function. Would they observe a similar effect of Finerenone in type 1 diabetics?
The researchers compared the changes in ACR at each time point across all participants and immediately saw a pattern. After three months both groups showed a reduction in ACR, but the Finerenone group already showed a 20% greater reduction than the placebo group.
At the six months point, on average, the difference in ACR between the placebo group and the drug group was 28%.
Is a 30% Change Good?
What does this mean? Well, patients who used Finerenone improved their kidney’s ability to filter for albumin by around 30% on average. It worked better for some than others, with 25% of participants hitting a 50% reduction in the amount of albumin in their urine. Just over half of participants treated with Finerenone reduced their ACR reading by at least 30% after six months. This is good news for people with type 1 diabetes who have been awaiting a verdict on Finerenone.
A 20% improvement in kidney function for someone already very poorly might look small to us outsiders, but it is clinically meaningful. Even a small reduction in ACR means the drug is not just stopping progression of damage but also helping to improve kidney function. Some of the participants were already quite poorly, so we expect that maybe those people might not respond as well to any treatment.
It’s also true that, for some people, the underlying cause of their kidney damage might be different. One of the challenges of developing new treatments is that there is still a lot for us to learn about how our bodies work and the different ways things can go wrong. This is why statistical power calculations are so important. It helps the researchers to account for the chances that some people’s symptoms look the same as the other participants, but have a different root cause.
The placebo group also showed a small change in ACR, of around 12%. Was this because the placebo helped? Perhaps, or perhaps just being in the trial and having more attention and more frequent tests made measurement variations more obvious.
Once participants stopped taking Finerenone, after 30 days their ACR levels returned to baseline – similar levels to the placebo group.
Did it Work?
Overall, this trial demonstrated that Finerenone could be a useful tool for type 1 diabetics at risk of developing renal failure. There were very few adverse events, none of them very serious – so the researchers determined that the drug is pretty safe at 10–20 mg per day.
Unfortunately, the demographics of the group skewed heavily towards White populations, meaning the results might not be generalizable. On the other hand, since regional phase 4 trials of Finerenone have shown that it works well for type 2 diabetics in Asia, it’s likely that subsequent testing will give similar effects for type 1 diabetics. Evidence-based medicine is an iterative process, and as researchers generate more trial data, doctors will better understand how best to prescribe the drug and who will benefit.
Chronic kidney disease is a serious complication of diabetes. Epidemiologists estimate at least half of diabetics have some kidney damage and one third or more people with diabetes will develop diabetic kidney disease. While Finerenone in combination with other drugs is a promising avenue for people already living with kidney disease, the best way for diabetics to keep their kidneys healthy is to stay on top of their blood glucose control and to work on keeping their cardiovascular system healthy.
People with type 2 diabetes have a chance to reverse the progression of their condition. It’s well documented that lifestyle changes that correlate with weight loss can help put your diabetes into remission, and as a result protect your kidneys from further damage.
References
Heerspink HJL, Birkenfeld AL, Cherney DZI, et al. Finerenone in Type 1 Diabetes and Chronic Kidney Disease. New England Journal of Medicine. 2026;394(10):947-957. doi:10.1056/NEJMoa2512854
Bakris GL, Agarwal R, Anker SD, et al. Effect of Finerenone on Chronic Kidney Disease Outcomes in Type 2 Diabetes. New England Journal of Medicine. 2020;383(23):2219-2229. doi:10.1056/NEJMoa2025845
Gheith O, Farouk N, Nampoory N, Halim MA, Al-Otaibi T. Diabetic kidney disease: world wide difference of prevalence and risk factors. J Nephropharmacol. 2015;5(1):49-56.