What is Diabetic Nephropathy (Kidney Disease)?

What is diabetic nephropathy (kidney disease)?

Diabetic nephropathy – also known as diabetic kidney disease – is a long-term complication of diabetes; both type 1 and type 2 – where high blood sugar damages the kidneys’ filtering units (glomeruli).

Most people will have had diabetes for at least 10 years before it starts. By this stage, diabetes will have usually started to damage the eyes (diabetic retinopathy) and nerve (diabetic neuropathy) and blood supply to the legs.

Over time, it can lead to chronic kidney disease (CKD) and even kidney failure – requiring dialysis or a kidney transplant.

How it happens

1. High blood sugar (hyperglycemia) damages tiny blood vessels in the kidneys.
2. The glomeruli, which filter waste from the blood, become thickened and scarred.
3. This leads to protein leakage into the urine (proteinuria or albuminuria).
4. Persistent damage eventually reduces kidney function.

Risk factors

• Poorly controlled blood sugar
• High blood pressure
• Long duration of diabetes
• Genetic predisposition (family history) – especially in Black or Asian people
• Smoking and obesity

Signs and symptoms

Early on, diabetic nephropathy often has no symptoms. Clues appear as the disease progresses:

• Protein in urine (often detected on lab tests before symptoms appear)
• Swelling in the legs, ankles, or around the eyes
• High blood pressure
• Fatigue due to buildup of toxins in the blood
• In advanced stages: nausea, vomiting, poor appetite, and confusion

Note. There are 5 stages of diabetic nephropathy. Not all patients progress to the more advanced stages.

Diagnosis

• Urine tests for albumin/protein (urinary ACR, uACR)
• Blood tests to check kidney function (creatinine, eGFR)
• Blood pressure monitoring
• A kidney biopsy is not normally required – unless the diagnosis is uncertain, e.g. proteinuria in someone with diabetes for 2 years

Treatment

There’s no cure, but progression can be slowed:

• Tight blood sugar control
• Blood pressure control (often using ACE inhibitors or ARBs, and SGLT2is)
• Cholesterol management
• Lifestyle changes: diet, exercise, quitting smoking
• In advanced kidney failure, dialysis or kidney transplant may be needed

Note. In people with Type 1 diabetes, a kidney and pancreas transplant is often a better option.

💡 Key difference from renovascular disease (RVD)

• Diabetic nephropathy is caused by damage inside the kidney (glomerular injury) due to diabetes.

• Renovascular disease is caused by reduced blood flow to the kidney (arterial narrowing), often triggering secondary high blood pressure.

Note. Some people with diabetes, will have both problems.