Causes

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

The exact cause is unknown. Poor control of blood sugar is thought to lead to kidney damage. If you also have high blood pressure, kidney damage is even more likely.

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.

Symptoms

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 kidney disease may have a poor appetite, feel tired most of the time, and have a general ill feeling.

Headache,nausea and vomiting,swelling of the legs, and many other symptoms may also occur.

See also: End stage kidney disease

Exams and Tests

Tests your doctor orders can often find signs of kidney problems in the early stages.

Once a year, you should have a urine test. It looks for a protein called albumin. Because the test looks for small amounts of albumin, it is sometimes called a test for microalbuminuria.

When you have diabetes, your doctor will test your urine for too much protein at least once a year. Too much protein is often a sign of kidney damage.

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

Other lab tests that may be done include:

• 24-hour urine protein
• Blood levels of phosphorus, calcium, bicarbonate, PTH, and potassium
• Hemoglobin
• Hematocrit
• Protein electrophoresis - urine

A kidney biopsy confirms the diagnosis. However, your doctor can often diagnose the condition without a biopsy. A biopsy is done if there is any doubt about the diagnosis.

Treatment

The goal of treatment is to keep the kidney disease from getting 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).

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

To help slow kidney damage, closely control your blood sugar levels by:

• Changing your diet
• 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 (ask your doctor and diabetes educator how often to check)

Urinary tract and other infections are common, and can be treated with antibiotics.

See also: Chronic kidney disease

Outlook (Prognosis)

Diabetic kidney disease is a major cause of sickness and death in people with diabetes.

When it is caught in the early stages, kidney damage may be slowed with treatment. Once larger amounts of protein appear in the urine, kidney damage will slowly get worse. Often, it will lead to the need for dialysis or a kidney transplant.

People with diabetic kidney disease often also have problems with high blood pressure, heart disease, and eye damage.

When to Contact a Medical Professional

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

Prevention

Before having an MRI, CT scan, or other imaging test where you may receive a contrast dye that contains iodine, tell your doctor. These dyes can further damage the kidneys.

Commonly used pain medicines, such as ibuprofen, naproxen, and prescription COX-2 inhibitors such as celecoxib (Celebrex) may injure the weakened kidney. Always talk to your health care provider before using any of these drugs.

Alternative Names

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

References

American Diabetes Association. Standards of medical care in diabetes--2011. Diabetes Care. 2011 Jan;34 Suppl 1:S11-61.

Inzucchi SE, Sherwin RS. Diabetes Mellitus. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 248.

American Diabetes Association (2004). Nephropathy in diabetes. Clinical Practice Recommendations 2004. Diabetes Care. 27(Suppl 1): S79�S83.

Parving H, Mauer M, Ritz E. Diabetic Nephropathy. In: Brenner BM. Brenner and Rector's The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 36.

Update Date: 1/3/2012

Reviewed by: A.D.A.M. Editorial: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Ari S. Eckman, MD, Chief, Division of Endocrinology, Diabetes and Metabolism, Trinitas Regional Medical Center, Elizabeth, NJ. Review provided by VeriMed Healthcare Network (6/28/2011).