From the Guidelines
Diabetic nephropathy is diagnosed through a combination of clinical assessment, laboratory tests, and sometimes imaging studies, with the initial screening including urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) as recommended by the most recent guidelines 1. The diagnosis of diabetic nephropathy requires a comprehensive approach, considering the presence of albuminuria and/or reduced eGFR in the absence of signs or symptoms of other primary causes of kidney damage.
- The typical presentation of diabetic kidney disease includes a long-standing duration of diabetes, retinopathy, albuminuria without gross hematuria, and gradually progressive loss of eGFR.
- Albuminuria is best assessed with spot urine samples to calculate the UACR, with a UACR of 30-300 mg/g indicating microalbuminuria (early nephropathy) and >300 mg/g suggesting macroalbuminuria (overt nephropathy) 1.
- Diagnosis requires at least two abnormal UACR tests over a 3-6 month period to confirm persistence, as transient albuminuria can occur with fever, exercise, or urinary tract infections.
- Annual screening should begin at diagnosis for type 2 diabetes and after 5 years of disease for type 1 diabetes, with serum creatinine measured to calculate eGFR, and values <60 mL/min/1.73m² indicating reduced kidney function 1.
- Renal ultrasound may be performed to rule out other causes of kidney disease, and referral to a nephrologist should be considered when there is uncertainty about the cause of kidney disease or advanced kidney disease 1.
- Early diagnosis is crucial as treatment with ACE inhibitors or ARBs, along with glycemic and blood pressure control, can significantly slow disease progression and improve outcomes.
- The most recent guidelines emphasize the importance of individualized care and consideration of patient-specific factors, such as comorbidities and medication side effects, when managing diabetic nephropathy 1.
From the Research
Diabetic Nephropathy Diagnosis
- Diabetic nephropathy, also known as diabetic kidney disease, is a common cause of kidney failure, affecting 20 to 30 percent of patients with diabetes 2.
- The most practical method of screening for microalbuminuria, an early stage of diabetic nephropathy, is to assess the albumin-to-creatinine ratio with a spot urine test 2.
- Results of two of three tests for microalbuminuria should be more than 30 mg per day or 20 mcg per minute in a three- to six-month period to diagnose a patient with diabetic nephropathy 2.
- Diabetic nephropathy is categorized into stages: microalbuminuria (UAE >20 microg/min and < or =199 microg/min) and macroalbuminuria (UAE > or =200 microg/min) 3.
Screening and Diagnosis
- Screening for microalbuminuria should be performed yearly, starting 5 years after diagnosis in type 1 diabetes or earlier in the presence of puberty or poor metabolic control 3.
- In patients with type 2 diabetes, screening should be performed at diagnosis and yearly thereafter 3.
- Spot urinary albumin to creatinine ratio (ACR) measurement has been suggested as a surrogate to 24-hr urine collection for the assessment of microalbuminuria 4.
- Serum cystatin C (cysC) is known as an advantageous marker for renal function and can be used for the assessment of diabetic nephropathy 4.
Diagnostic Criteria
- Persistent albuminuria and a progressive decline in renal function are characteristic of diabetic nephropathy 5.
- The term diabetic kidney disease (DKD) is now commonly used to encompass the spectrum of people with diabetes who have either albuminuria or reductions in renal function 5.
- Hyperglycemia, increased blood pressure levels, and genetic predisposition are the main risk factors for the development of diabetic nephropathy 3.