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Diabetic nephropathy is kidney disease or damage that can occur in people with diabetes.

Kimmelstiel-Wilson disease; Diabetic glomerulosclerosis; Nephropathy - diabetic; Diabetic nephropathy

Each kidney is made of hundreds of thousands of small units called nephrons. These structures filter your blood and help remove waste from your body.

In people with diabetes, the nephrons thicken and slowly become scarred over time.

• The kidneys begin to leak and protein (albumin) passes into the urine.
• This damage can happen years before any symptoms begin.
• The exact cause is unknown. However, kidney damage is more likely if there is poor control of diabetes and high blood pressure.

In some cases, your family history may also play a role. Not everyone with diabetes develops this kidney problem.

People with diabetes who smoke, and those with type 1 diabetes that started before age 20 have a higher risk for kidney problems.

People of African-American, Hispanic, and American Indian origin are also more likely to have kidney damage.

Often, there are no symptoms as the kidney damage starts and slowly gets worse. Kidney damage can begin 5 to 10 years before symptoms start.

People who have more severe and long-term (chronic) kidney disease may have symptoms such as:

• Fatigue most of the time
• General ill feeling
• Headache
• Nausea and vomiting
• Poor appetite
• Swelling of the legs 

Your doctor can order tests to detect signs of kidney problems in the early stages. Once a year, you should have a urine test. It looks for a protein called albumin leaking into the urine.

• Too much of this protein leaking is often a sign of kidney damage.
• Because the test looks for small amounts of albumin, it is sometimes called a test for microalbuminuria.

High blood pressure often goes along with diabetic nephropathy. You may have high blood pressure that begins quickly or is hard to control.

Your doctor will also check your kidneys with the following blood tests every year:

• BUN
• Serum creatinine

A kidney biopsy confirms the diagnosis. A biopsy is done only if there is any doubt about the diagnosis.

When kidney damage is caught in its early stages, it can be slowed with treatment. Once larger amounts of protein appear in the urine, kidney damage will slowly get worse.

Keeping your blood pressure under control (under 130/80) is one of the best ways to slow kidney damage.

• Your doctor may prescribe medicines to lower your blood pressure and protect your kidneys from more damage. Often, the best types of medicine to use are ACE inhibitors and angiotensin receptor blockers (ARBs).
• Even when your blood pressure is normal, these medicines will help slow kidney damage.

Eating a low-fat diet, taking drugs to control blood cholesterol, and getting regular exercise can also help prevent or slow kidney damage.

You can also slow kidney damage by controlling your blood sugar levels, which you can do by:

• Eating a healthy diet
• Regularly taking insulin or other medicines your doctor prescribes
• Knowing the basic steps for managing your blood sugar levels at home
• Checking your blood sugar levels and keeping a record of them

To protect your kidneys, remember the following:

• Tell your doctor about your diabetes before having an MRI, CT scan, or other imaging test in which you receive a contrast dye. These dyes can further damage the kidneys.
• Always talk to your health care provider before taking NSAID pain medicines, such as ibuprofen and naproxen. They can damage the kidneys.
• Know the signs of urinary tract infections and get treated right away.

To treat chronic kidney disease, you need to make changes to your diet, and treat problems caused by kidney disease.

Diabetic kidney disease is a major cause of sickness and death in people with diabetes. It can lead to the need for dialysis or a kidney transplant.

Call your health care provider if you have diabetes and you have not had a routine urinalysis to check for protein.

American Diabetes Association. Standards of medical care in diabetes--2012. Diabetes Care. 2012 Jan;35 Suppl 1:S11-63.

Parving H, Mauer M, Fioretto P, Rossing P, Ritz E. Diabetic Nephropathy. In: Taal MW, Chertow GM, Marsden PA, Skorecki K, Yu ASL, Brenner BM, eds. Brenner and Rector's The Kidney. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011: chap 38.