How does diabetes affect the kidneys?
Your kidneys filter blood through millions of tiny vessels. Over years, high blood sugar damages those vessels and the delicate filters they supply, called glomeruli. The kidneys begin to leak protein into the urine and gradually filter less well. This is diabetic kidney disease, sometimes called diabetic nephropathy — and it is the single most common cause of kidney failure.
It develops slowly, which is both the danger and the opportunity: it’s easy to miss, but there is time to protect your kidneys if you catch it early. Both type 1 and type 2 diabetes can cause it, and the risk rises the longer blood sugar runs high and when blood pressure is also elevated.
The first sign is a number, not a symptom
Like most kidney problems, diabetic kidney disease is silent at first. The earliest sign is albumin (a protein) appearing in the urine — something you can’t feel, only measure. This is why screening is everything.
If you have type 1 or type 2 diabetes, you should have two simple tests at least once a year:
A urine test that catches albumin early — often the very first clue, years before symptoms.
A blood test that estimates filtering. Tracked over time, it shows whether the kidneys are holding steady.
These tests can catch kidney disease years before you’d notice anything — when there’s the most to gain from acting. In general, screening starts at diagnosis for type 2 diabetes, and about five years after diagnosis for type 1, then continues yearly. If a test comes back abnormal, it’s usually repeated to confirm it isn’t a temporary blip — a single high reading can be caused by a fever, hard exercise, or dehydration. Once confirmed, an abnormal result isn’t a dead end; it’s the signal to start protecting your kidneys.
What are the symptoms of diabetic kidney disease?
In its early and most treatable stages, there are no symptoms. That’s the whole reason screening matters. As the disease advances, signs can appear:
- Swelling in the ankles, feet, or around the eyes
- Foamy or bubbly urine, a sign of protein leaking
- Rising blood pressure that gets harder to control
- Fatigue, poor appetite, and trouble concentrating
- A need for less diabetes or blood-pressure medication than before, as failing kidneys change how the body handles them
By the time these appear, the disease is usually well established — which is exactly why waiting for symptoms is the wrong strategy, and a yearly test is the right one.
How far has it progressed?
Diabetic kidney disease is staged the same way as other chronic kidney disease — by your two numbers together. Your eGFR places you in a stage from G1 (normal filtering) to G5 (kidney failure), while your urine albumin (uACR) describes how much protein is leaking. Two people with the same eGFR can be at very different risk depending on their protein level.
The goal of staging isn’t to alarm you — it’s to match the strength of treatment to your actual risk, and to track whether what you’re doing is working.
Most people with diabetic kidney disease are found in the earlier stages, where the most can be done. For a full explanation of eGFR, uACR, and the stages, see our chronic kidney disease guide.
Can diabetic kidney disease be reversed?
This is the question patients ask most, and the honest answer has two parts. The existing damage usually can’t be undone. But its progress can often be slowed dramatically — and in the earliest stage, when only small amounts of protein are leaking, good control can sometimes bring those levels back down. The earlier it’s found, the more can be done. That’s the whole case for screening, and it’s why catching diabetic kidney disease early is one of the most valuable things routine diabetes care can do for you.
How it’s treated — including what’s new
Treatment aims to protect the kidneys and slow the damage. The foundation is familiar: keep blood sugar and blood pressure in healthy ranges, eat well, stay active, and don’t smoke. For many people that means an A1C around 7% (your doctor may set a different target) and blood pressure under about 130/80.
What’s changed — and what makes today genuinely different — is medication. Several classes now protect the kidneys directly in people with diabetes, and current national guidelines increasingly recommend using them together, in “pillars,” much like modern heart-failure care:
ACE inhibitors & ARBs
The long-standing foundation when protein is in the urine — they lower blood pressure and reduce protein leakage.
SGLT2 inhibitors
Originally diabetes drugs, now a cornerstone — proven to slow kidney decline and protect the heart in people with kidney disease.
Finerenone
A newer nonsteroidal medication that further lowers kidney and heart risk for many with type 2 diabetes and kidney disease. Requires potassium monitoring.
GLP-1 receptor agonists
Help with blood sugar and weight, and show kidney-protective benefits. A statin is usually added to lower cardiovascular risk.
Used together and started early, these have meaningfully changed the outlook for diabetic kidney disease — slowing it more than any single drug can on its own. Which combination is right depends on your kidney numbers, your other conditions, and your potassium levels, which is part of what a nephrologist sorts out. For more, see our page on advanced therapies for slowing CKD.
Have diabetes and want your kidneys checked, or to know if you're a candidate for the newer medications?
Request an AppointmentProtecting your kidneys day to day
Medications do a lot, but daily habits still matter — and they’re within your control:
- Keep blood sugar and blood pressure near your targets — the two biggest levers you have.
- Take kidney-protective medications as prescribed, even though you won’t feel them working.
- Be careful with over-the-counter NSAIDs like ibuprofen and naproxen, which can stress the kidneys — ask before using them regularly.
- Don’t smoke, which accelerates kidney and blood-vessel damage.
- Stay active and eat well — a kidney-friendly, lower-sodium diet helps; a dietitian can tailor it to you.
- Get your yearly uACR and eGFR, and know your numbers.
Common myths about diabetes and the kidneys
If my kidneys were affected, I’d feel it.
Early diabetic kidney disease is silent. A urine test finds it long before any symptom would.
My sugars are fine, so my kidneys are fine.
Good control lowers the risk but doesn’t remove it — and blood pressure and time also play a part. Yearly screening is still the only way to know.
There’s nothing to do but wait for dialysis.
Today there’s more that can be done than ever. Several medications now actively slow the disease, and many people never reach dialysis.
Kidney damage from diabetes is quick.
It usually takes years — which is exactly why early, consistent care can change the whole trajectory.
When should you see a nephrologist?
Many people with diabetes are screened and managed well by their primary care doctor or endocrinologist. It’s worth adding a kidney specialist when:
- Your eGFR is under 60 and persists or is declining
- You have protein in the urine (an elevated uACR), especially if it’s rising
- Your blood pressure is hard to control
- You’d benefit from a clear plan using the newer kidney-protective medications
- You want a second opinion on protecting your kidneys
Earlier kidney care consistently leads to better outcomes. Seeing a nephrologist doesn’t mean things are dire — often it’s the opposite, a chance to act while there’s the most to protect.
