Diabetic kidney disease, also called diabetic nephropathy, is one of the most common complications of long-term diabetes. It develops slowly, often without obvious symptoms in the early stages. That's why knowing the warning signs is so important — catching it early can make a real difference in preserving kidney function.
The kidneys filter waste and excess fluid from your blood. When high blood sugar damages the tiny blood vessels inside them, they start to leak protein and lose their filtering ability. Over time, this can lead to chronic kidney disease and, eventually, kidney failure. Here are seven warning signs that experts say you should not ignore.
1. Swelling in the feet, ankles, or hands
When your kidneys are not filtering properly, sodium and fluid build up in your body. This often shows up as puffiness or swelling — known medically as edema — especially in the lower legs, feet, ankles, and sometimes the hands or face. The swelling may be mild at first, coming and going, but it can become more persistent as kidney function declines.
2. Foamy or bubbly urine
One of the earliest detectable signs of kidney damage is protein in the urine, or proteinuria. Healthy kidneys keep protein in the blood, but damaged filters let it leak out. This extra protein makes urine look foamy or frothy, similar to what you might see when eggs are whisked. It's not always present at every urination, so noticing it even occasionally is worth mentioning to your doctor.
3. Markedly increased fatigue
Kidneys produce a hormone called erythropoietin, which signals your body to make red blood cells. When kidneys are damaged, they produce less of this hormone, leading to anemia. This can cause persistent tiredness, weakness, and trouble concentrating — even if you are sleeping enough. Many people mistake this fatigue for a normal part of aging or a busy life, but it can be a clue that the kidneys are struggling.
4. Shortness of breath unrelated to exercise
Fluid that your kidneys cannot remove can build up in your lungs, making it harder to breathe. Additionally, anemia reduces the amount of oxygen in your blood, which can also trigger shortness of breath. If you find yourself winded after light activity — or even at rest — and you have diabetes, kidney issues should be on your radar.
5. A metallic taste in the mouth or changes in appetite
Waste accumulation in the blood (uremia) can alter your sense of taste, often causing a metallic or foul taste. You might also notice a loss of appetite or an aversion to protein-rich foods like meat. This can lead to unintentional weight loss over time, which is another signal that kidney function may be declining.
6. Persistent itching or very dry skin
Kidneys help balance minerals and minerals in your blood. When they are not working well, imbalances — particularly high phosphorus levels — can cause intense itching and extremely dry skin. This itching is often worse at night and does not respond well to lotions or moisturizers. It can affect the back, arms, and legs.
7. Uncontrolled blood pressure that is hard to manage
The kidneys play a central role in regulating blood pressure. When they are damaged, blood pressure often rises and becomes harder to control with medications that used to work. Uncontrolled hypertension, in turn, accelerates kidney damage — a vicious cycle. If your blood pressure numbers are creeping up despite lifestyle changes and medication, it is worth asking your doctor to check your kidney function.
Important: Diabetic kidney disease often has no symptoms until it is fairly advanced. Regular urine and blood tests (like the eGFR and UACR) are the best way to catch it early. The National Kidney Foundation recommends that people with diabetes get these tests at least once a year.
When to see a doctor
If you have diabetes and notice any of the warning signs above, do not wait for your next scheduled appointment. Contact your healthcare provider. They can run simple tests to check your kidney function — a urine test for protein (albuminuria) and a blood test for creatinine (used to calculate your estimated glomerular filtration rate, or eGFR). Early treatment can slow the progression of kidney disease and help you avoid dialysis or a kidney transplant.
The good news is that managing your blood sugar, blood pressure, and cholesterol — along with a kidney-friendly diet and regular monitoring — can significantly lower your risk of developing diabetic kidney disease or delay its progression. You are the most important person on your care team.
