How Can Diabetes Affect Kidney Health?

How Can Diabetes Affect Kidney Health?

Diabetes is the leading cause of chronic kidney disease and kidney failure in many countries. Around one in three adults with diabetes develops some degree of kidney damage, called diabetic kidney disease or diabetic nephropathy. It develops slowly and quietly, often with no symptoms until the damage is advanced, which is why regular testing matters. The good news is that with early detection, good blood sugar and blood pressure control, and the right medicines, most people can slow or even prevent the progression of kidney damage.

This guide explains what the kidneys do, how diabetes damages them, the stages and warning signs, how kidney disease is detected, and what you can do to protect your kidneys.

What Do the Kidneys Do?

Your two kidneys filter waste and excess fluid from the blood, balance salts and minerals, help control blood pressure, make hormones that support red blood cell production and bone health, and keep the body’s chemistry stable. Each kidney contains about a million tiny filters called glomeruli, supplied by very small blood vessels. These are the structures that diabetes damages.

How Diabetes Damages the Kidneys

1. High Blood Sugar Harms the Filters

Persistently high blood glucose damages the small blood vessels in the glomeruli, making them leaky and scarred. Over time they filter less effectively.

2. High Blood Pressure

Diabetes and high blood pressure often occur together, and high pressure puts extra strain on the kidney filters. It is both a cause and a consequence of kidney damage.

3. Protein Leakage

Damaged filters allow protein, particularly albumin, to leak into the urine. This is one of the earliest signs of diabetic kidney disease, and the leaked protein can itself further injure the kidney.

4. Other Factors

• Inflammation and oxidative stress.
• High cholesterol and obesity.
• Smoking.
• Genetic susceptibility.
• Repeated urinary tract infections and some medicines that can strain the kidneys.

Stages of Diabetic Kidney Disease

Kidney function is measured by the estimated glomerular filtration rate (eGFR), and kidney damage is detected by albumin in the urine. Chronic kidney disease is divided into stages:

• Early stages: Mildly reduced function or small amounts of urine albumin, with no symptoms. This is the best time to intervene.
• Moderate stages: More significant loss of function. Symptoms may start to appear.
• Advanced stages: Severe loss of function, with many symptoms.
• Kidney failure (end-stage): Kidneys can no longer sustain life, and dialysis or a kidney transplant is needed.

Symptoms and Warning Signs

Early kidney disease usually causes no symptoms. As it progresses, signs may include:

• Foamy urine, from protein.
• Swelling in the feet, ankles, hands, or around the eyes.
• Tiredness and weakness.
• Loss of appetite, nausea, or a metallic taste.
• Itchy skin.
• Frequent urination, particularly at night, or reduced urine output.
• Shortness of breath.
• Muscle cramps.
• Difficulty concentrating.
• Rising blood pressure.
• Reduced need for insulin or diabetes medicines, because damaged kidneys clear them less effectively. This can cause unexpected low blood sugar.

Because symptoms appear late, screening is essential.

How Is Kidney Disease Detected?

• Urine albumin-to-creatinine ratio (UACR): Detects protein leakage, the earliest sign.
• Blood test for creatinine and eGFR: Measures how well the kidneys filter.
• Blood pressure measurement.
• Imaging or biopsy: Occasionally needed if the cause is unclear.

People with type 2 diabetes should be tested at diagnosis and then at least once a year. People with type 1 diabetes should be tested yearly starting about five years after diagnosis, or earlier in some cases.

Who Is at Higher Risk?

• Long duration of diabetes.
• Poor blood sugar control.
• High blood pressure.
• High cholesterol or obesity.
• Smoking.
• Family history of kidney disease.
• Presence of other complications, such as eye disease or neuropathy.
• Certain ethnic backgrounds, including South Asian, African, Hispanic, and Indigenous populations.

How to Protect Your Kidneys

1. Control Blood Sugar

Good glucose control reduces the risk of kidney damage and slows progression. Work with your care team on targets and medicines. See simple tips for better diabetes management.

2. Control Blood Pressure

Aim for the target your doctor sets, commonly below 130/80 mmHg. Medicines called ACE inhibitors or angiotensin receptor blockers (ARBs) are often used, because they lower blood pressure and also reduce protein leakage and protect the kidneys.

3. Consider Kidney-Protective Medicines

Some newer diabetes medicines, such as SGLT2 inhibitors, and certain other drugs have been shown to slow kidney disease progression and reduce heart risks in people with diabetes and kidney disease. Ask your doctor whether they are right for you.

4. Eat Kidney-Friendly Foods

• Follow a balanced, heart-healthy diet with vegetables, fruit, whole grains, and legumes.
• Limit salt, ideally under about 5 to 6 grams a day.
• Avoid excess protein if advised. Needs vary, and a dietitian can help.
• If kidney function falls, you may need to limit potassium and phosphorus.
• Limit processed and sugary foods.

See the best foods to help manage blood sugar, and speak to a dietitian about adjustments for kidney health.

5. Stay Active and Keep a Healthy Weight

Regular exercise and weight control help blood sugar, blood pressure, and kidney health.

6. Do Not Smoke

Smoking speeds up kidney damage.

7. Limit Alcohol

Keep within recommended limits.

8. Be Careful With Medicines

Some painkillers, particularly non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and diclofenac, can harm the kidneys, especially with dehydration or existing kidney disease. Check with your doctor or pharmacist before using them. Also avoid unregulated herbal products. Contrast dye used in some scans may need precautions.

9. Stay Hydrated and Treat Infections Promptly

Drink enough fluids unless told to restrict them, and seek treatment for urinary infections.

10. Have Regular Check-Ups

Attend annual urine and blood tests, and regular blood pressure, cholesterol, eye, and foot checks.

Treatment for Advanced Kidney Disease

If kidney function declines significantly, care may involve:

• Close monitoring by a kidney specialist (nephrologist).
• Medicines to control blood pressure, cholesterol, anaemia, and bone and mineral problems.
• Dietary changes.
• Dialysis, which filters the blood artificially.
• Kidney transplant for suitable patients.

Many people with advanced kidney disease still live full lives with the right support.

Kidneys, Heart, and Diabetes Are Linked

Kidney disease raises the risk of heart disease, and heart disease and high blood pressure can worsen kidney disease. Protecting one protects the others. See how diabetes affects your heart health.

Sick-Day Rules for the Kidneys

When you have vomiting, diarrhoea, or fever, dehydration can strain the kidneys. Ask your doctor whether certain medicines, such as metformin, ACE inhibitors, ARBs, SGLT2 inhibitors, and diuretics, should be paused temporarily, and when to restart them. Do not stop them without advice.

When to See a Doctor

See a doctor if you have diabetes and have not had a recent kidney test, or if you notice foamy urine, swelling, unusual tiredness, changes in urination, or rising blood pressure. Seek urgent care for very little or no urine, severe swelling, difficulty breathing, confusion, or chest pain.

Frequently Asked Questions

Can kidney damage from diabetes be reversed?

Early damage can sometimes improve with good control, but advanced damage usually cannot be reversed. Early action is key.

How often should I be tested?

At least once a year.

Will I need dialysis?

Not necessarily. Many people never reach kidney failure, particularly with early and good care.

Final Thoughts

Diabetes can damage the kidneys silently over years, but you can protect them. Get tested every year, control blood sugar and blood pressure, take kidney-protective medicines when advised, eat well, do not smoke, and be careful with painkillers. Early detection and consistent care keep your kidneys working for longer.

This article is for general information only and is not a substitute for professional medical advice.