Diabetic Nephropathy

Diabetic nephropathy, now usually called diabetic kidney disease, is kidney damage caused by diabetes. Years of high blood sugar and high blood pressure damage the kidneys' filters, so protein leaks into the urine and kidney function slowly falls. It is one of the leading causes of kidney failure. It usually causes no symptoms until it is advanced, when swelling, tiredness and foamy urine can appear. Good control of blood sugar and blood pressure, and some medicines such as SGLT2 inhibitors and ACE inhibitors or ARBs, can slow it.

Lab tests linked to diabetic nephropathy:

• Creatinine, serum: used to calculate the estimated glomerular filtration rate (eGFR), a measure of kidney function.
• Protein, total, random urine and protein/creatinine ratio: measure protein lost in the urine.
• Screening uses the urine albumin-to-creatinine ratio (ACR) and eGFR, at least once a year for most people with diabetes. Doctors also check HbA1c, blood pressure, potassium and lipids.

How results are read:

• A urine ACR of 30 mg/g or higher, or an eGFR below 60 mL/min/1.73 m², lasting at least 3 months, shows chronic kidney disease.
• A raised ACR is confirmed on 2 of 3 samples over 3 to 6 months, because exercise, infection, fever and high blood sugar can raise it briefly.
• Rapidly rising protein, blood in the urine, or a quick fall in eGFR can point to another kidney disease, and may need specialist tests.

When to see a doctor:

• If you have diabetes, ask for yearly urine ACR and eGFR tests.
• See a doctor about swelling of the ankles or legs, foamy urine, or passing much less urine.
• Get emergency care for severe breathlessness, confusion, or chest pain.

Clinical takeaway: diabetic kidney disease is found with yearly urine ACR and eGFR tests, and finding it early allows treatment that slows kidney damage.