Diabetes and Kidney Disease: Symptoms, Tests, Prevention and Treatment

About one in three people with diabetes develops diabetic kidney disease (diabetic nephropathy), and it is one of the leading causes of kidney failure worldwide. The kidneys contain millions of tiny filters. Over years, high blood sugar and high blood pressure damage these filters, and they begin leaking protein and filtering less well. The process is slow and silent, but it is highly preventable and treatable if found early.

Early signs: usually none

In the early stages there are no symptoms. As kidney function falls, people may notice:

• Foamy or bubbly urine (from protein)
• Swelling of the feet, ankles, hands or around the eyes
• Tiredness, weakness and pallor (anaemia)
• Poor appetite, nausea, a metallic taste
• Itching
• High blood pressure that is hard to control
• Shortness of breath from fluid
• Passing less urine, or needing less insulin than before (the failing kidney clears insulin more slowly)

By the time these appear, the damage is often advanced. This is why testing is needed, even when you feel well.

Tests every person with diabetes needs

1. Urine albumin-to-creatinine ratio (ACR): detects small amounts of protein in the urine. A value of 30 mg/g (3 mg/mmol) or more on repeated tests suggests kidney damage. Dipstick tests miss early leakage.
2. Blood creatinine and eGFR: eGFR estimates how well the kidneys filter. A value below 60 mL/min for three months or longer indicates chronic kidney disease.
3. Blood pressure, at every visit.

Everyone with type 2 diabetes should have these tests at diagnosis and then at least once a year. In type 1 diabetes, begin about five years after diagnosis, or from puberty.

Stages of kidney disease

Chronic kidney disease is staged from 1 to 5 by eGFR and protein leakage. Stages 1-2 have normal or mildly reduced function, stage 3 is moderate, stage 4 is severe, and stage 5 (eGFR below 15) is kidney failure needing dialysis or transplantation.

How to protect your kidneys

1. Control blood sugar. Keeping HbA1c near target reduces the risk of kidney damage. See our HbA1c guide. Avoid very low sugars, which are more likely when kidney function falls.

2. Control blood pressure. The target for most people with diabetic kidney disease is below 130/80 mmHg. See how to lower high blood pressure.

3. Use kidney-protecting medicines:

• ACE inhibitors or ARBs reduce protein leakage and slow progression. They are first-line for people with high blood pressure and protein in the urine. Kidney tests and potassium are checked after starting.
• SGLT2 inhibitors (such as empagliflozin and dapagliflozin) lower sugar modestly but have strong kidney and heart protection, even when eGFR is reduced.
• Finerenone may be added in some people with type 2 diabetes and persistent protein in the urine.
• GLP-1 agonists help with weight and heart protection.
• Statins protect the heart, since people with kidney disease have high cardiovascular risk.

4. Be careful with other medicines. Avoid regular NSAID painkillers (diclofenac, ibuprofen, mefenamic acid), and avoid herbal remedies of uncertain safety. Tell any doctor about your kidney disease before scans using contrast dye, new antibiotics or surgery. Some diabetes drugs need dose changes.

5. Eat for kidney health.

• Reduce salt (below 5 g, about a teaspoon, a day), including dried fish, pickles and processed food.
• Eat a balanced diet with vegetables, pulses, fish and whole grains.
• Do not eat excess protein, but do not cut it drastically without advice; most people benefit from a moderate intake.
• If potassium or phosphate are high on blood tests, a dietitian may advise limiting certain foods.
• Stay hydrated, but if you have swelling or advanced disease, follow your doctor's fluid advice.

6. Healthy lifestyle. Stop smoking, keep a healthy weight (see BMI for Asians), and walk daily.

Other kidney risks in Sri Lanka

Chronic kidney disease of unknown cause (CKDu) affects farming communities in some dry-zone areas. People with diabetes living or working in those areas should have regular kidney checks and avoid unregulated herbal or pain medicines. Also treat urine infections promptly.

When kidney disease advances

In later stages, the kidney team treats anaemia, bone and mineral problems, acidosis and fluid overload, and discusses options: haemodialysis, peritoneal dialysis, kidney transplantation, or conservative care. Early referral to a nephrologist gives time for planning and often a better outcome.

Seek urgent care for

Marked breathlessness, chest pain, severe swelling, very little or no urine, confusion, persistent vomiting, or a very high potassium level. People with kidney disease and diabetes should also seek help early during illness with vomiting or diarrhoea, as dehydration can injure the kidneys.

When to see a doctor

See a doctor for annual kidney screening, and sooner if your eGFR is falling, protein appears in the urine, your blood pressure rises, or you notice swelling or foamy urine. Read also about the other complication checks, including diabetic foot care.

References

• KDIGO: clinical practice guideline for diabetes management in chronic kidney disease
• American Diabetes Association: Standards of Care in Diabetes, chronic kidney disease and risk management
• International Diabetes Federation: Diabetes Atlas
• Sri Lanka Ministry of Health: national guidance on chronic kidney disease