Throughout its early course, diabetic nephropathy has no symptoms. Symptoms develop in late stages and may be a result of excretion of high amounts of protein in the urine or due to renal failure:

• swelling -- usually around the eyes in the mornings; later, general body swelling may result
• foamy appearance or excessive frothing of the urine
• unintentional weight gain (from fluid accumulation)
• swelling of the legs
• poor appetite
• nausea and vomiting
• general ill feeling
• fatigue
• headache
• frequent hiccups
• generalized itching
  

The first laboratory abnormality is a positive microalbuminuria test. This means you are very likely to develop diabetic nephropathy.

Most often, the diagnosis is suspected when a routine urinalysis of a person with diabetes shows too much protein in the urine (proteinuria). The urinalysis may also show glucose in the urine, especially if blood glucose is poorly controlled.
There may or may not be signs of other diabetic complications. High blood pressure may be present or develop rapidly and may be difficult to control. Serum creatinine and BUN may increase as kidney damage progresses.

A kidney biopsy confirms the diagnosis. Most nephrologists do not need to perform the biopsy if the case is straightforward, with a documented progression of proteinuria over time and presence of diabetic retinopathy on examination of the retina of the eyes. Should there be any doubt in the diagnosis, a biopsy may be performed to confirm the diagnosis and to study the extent of the disease.

This disease may also alter the results of the following tests:

• protein electrophoresis - urine
• creatinine - urine
• 24-hour urine protein