Diabetic nephropathy is kidney disease or damage that results as a complication of diabetes.
Kimmelstiel-Wilson disease; Diabetic glomerulosclerosis; Nephropathy - diabetic
Causes, incidence, and risk factors
The exact cause of diabetic nephropathy is unknown, but it is believed that uncontrolled high blood sugar leads to the development of kidney damage, especially when high blood pressure is also present. In some cases, your genes or family history may also play a role. Not all persons with diabetes develop this condition.
Each kidney is made of hundreds of thousands of filtering units called nephrons. Each nephron has a cluster of tiny blood vessels called a glomerulus. Together these structures help remove waste from the body. Too much blood sugar can damage these structures, causing them to thicken and become scarred. Slowly, over time, more and more blood vessels are destroyed. The kidney structures begin to leak and protein (albumin) begins to pass into the urine.
Persons with diabetes who have the following risk factors are more likely to develop this condition:
- African American, Hispanic, or American Indian origin
- Family history of kidney disease or high blood pressure
- Poor control of blood pressure
- Poor control of blood sugars
- Type 1 diabetes before age 20
Diabetic nephropathy generally goes along with other diabetes complications including high blood pressure, retinopathy, and blood vessel changes.
Early stage diabetic nephropathy has no symptoms. Over time, the kidney's ability to function starts to decline. Symptoms develop late in the disease and may include:
- Foamy appearance or excessive frothing of the urine
- Frequent hiccups
- General ill feeling
- Generalized itching
- Nausea and vomiting
- Poor appetite
- Swelling of the legs
- Swelling, usually around the eyes in the mornings; general body swelling may occur with late-stage disease
- Unintentional weight gain (from fluid buildup)
Signs and tests
The main sign of diabetic nephropathy is persistent protein in the urine. (Protein may appear in the urine for 5 to 10 years before other symptoms develop.) If your doctor thinks you might have this condition, a microalbuminuria test will be done. A positive test often means you have at least some damage to the kidney from diabetes. Damage at this stage may be reversible. The test results can be high for other reasons, so it needs to be repeated for confirmation.
High blood pressure often goes along with diabetic nephropathy. You may have high blood pressure that develops rapidly or is difficult to control.
Laboratory tests that may be done include:
The levels of these tests will increase as kidney damage gets worse. Other laboratory tests that may be done include:
- 24-hour urine protein
- Blood levels of phosphorus, calcium, bicarbonate, PTH, and potassium
- Protein electrophoresis - urine
A kidney biopsy confirms the diagnosis. However, your doctor can diagnose the condition without a biopsy if you meet the following three conditions:
- Persistent protein in the urine
- Diabetic retinopathy
- No other kidney or renal tract disease
A biopsy may be done, however, if there is any doubt in the diagnosis.
The goals of treatment are to keep the kidney disease from getting worse and prevent complications. This involves keeping your blood pressure under control (under 130/80). Controlling high blood pressure is the most effective way of slowing kidney damage from diabetic nephropathy.
Your doctor may prescribe the following medicines to lower your blood pressure and protect your kidneys from damage:
- Angiotensin-converting enzyme (ACE) inhibitors
- Angiotensin receptor blockers (ARBs)
These drugs are recommended as the first choice for treating high blood pressure in persons with diabetes and for those with signs of kidney disease.
It is also very important to control lipid levels, maintain a healthy weight, and engage in regular physical activity.
You should closely monitor your blood sugar levels. Doing so may help slow down kidney damage, especially in the very early stages of the disease. Your can change your diet to help control your blood sugar. See also: Diet for people with diabetes
Depending on how poorly your kidneys are working, your doctor may limit the amount of protein in your diet. See: Diet for chronic kidney disease
Your doctor may also prescribe medications to help control your blood sugar. Your dosage of medicine may need to be adjusted from time to time. As kidney failure gets worse, your body removes less insulin, so smaller doses may be needed to control glucose levels.
Urinary tract and other infections are common and can be treated with appropriate antibiotics.
Dialysis may be necessary once end-stage kidney disease develops. At this stage, a kidney transplant may be considered. Another option for patients with type 1 diabetes is a combined kidney-pancreas transplant.
Nephropathy is a major cause of sickness and death in persons with diabetes. It is the leading cause of long-term kidney failure and end-stage kidney disease in the United States, and often leads to the need for dialysis or kidney transplantation.
The condition slowly continues to get worse once large amounts of protein begin to appear in the urine or levels of creatinine in the blood begin to rise.
Complications due to chronic kidney failure are more likely to occur earlier, and get worse more rapidly, when it is caused by diabetes than other causes. Even after dialysis or transplantation, persons with diabetes tend to do worse than those without diabetes.
Possible complications include:
Calling your health care provider
Call your health care provider if you have diabetes and a routine urinalysis shows protein.
Call your health care provider if you develop symptoms of diabetic nephropathy, or if new symptoms develop, including little or no urine output.
All persons with diabetes should have a yearly checkup with their doctor to have their blood and urine tested for signs of possible kidney problems.
Persons with kidney disease should avoid contrast dyes that contain iodine, if possible. These dyes are removed through the kidneys and can worsen kidney function. Certain imaging tests use these types of dyes. If they must be used, fluids should be given through a vein for several hours before the test. This allows for rapid removal of the dyes from the body.
Commonly used nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, naproxen, and prescription COX-2 inhibitors such as celecoxib (Celebrex), may injure the weakened kidney. You should always talk to your health care provider before using any drugs
American Diabetes Association. Standards of medical care in diabetes--2010. Diabetes Care. 2010 Jan;33 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.
Reviewed By: Charles Silberberg, DO, Private Practice specializing in Nephrology, Affiliated with New York Medical College, Division of Nephrology, Valhalla, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.