Diabetic nephropathy is kidney damage that occurs as a result of diabetes. Diabetic nephropathy causes illness and sometimes death for people with diabetes. Diabetes affects approximately seven percent of people in the United States. In fact, diabetes is the leading cause of chronic kidney disease (CKD) and kidney failure in the nation.
People who already have diabetes are susceptible to developing diabetic nephropathy if they:
- are of African American, Hispanic or Native and Alaskan American origin
- have a family history of kidney disease or high blood pressure
- have poor control of blood sugar
- had type 1 diabetes before age 20
- are a smoker
Not everyone with diabetes develops chronic kidney disease, but researchers believe that those who do not properly control their blood glucose levels are at risk. The kidneys are each made up of around 1 million nephrons that remove extra fluid and wastes out from the blood. These nephrons help regulate water, salts, glucose, urea, phosphorus and other minerals. Those with diabetes have a lot of glucose that comes out in their urine. High blood sugar levels can damage the tiny blood vessels in the nephrons by thickening and scarring them so that over time they are damaged. When this happens, protein leaks through the kidneys into the urine. The nephrons are no longer able to filter properly and this is when kidneys damage can lead to kidney failure.
Symptoms of diabetic nephropathy
In the beginning stages of diabetic nephropathy, people may not experience any symptoms. Symptoms of diabetic nephropathy are similar to symptoms of chronic kidney disease and tend to occur in the late stages of kidney disease.
These symptoms include:
- A metallic taste in the mouth or ammonia breath
- Nausea and vomiting
- Loss of appetite
- No longer wanting to eat meat (protein aversion)
- Difficulty concentrating
- Itchiness (pruritis)
- Swelling in the face, feet or hands
- Shortness of breath (from low level of red blood cells or fluid in the lungs)
- Making more or less urine than usual
- Urine that is foamy or bubbly (may be seen when protein is in the urine)
- Blood in the urine (typically only seen through a microscope)
- Anemia (low hemoglobin or level of red blood cells)
- Fatigue and weakness
- Feeling cold all the time
- Mental confusion
- Desire to chew ice, clay or laundry starch (this is called pica)
Diagnosing diabetic nephropathy
It is common for a doctor to check for diabetic nephropathy in someone with diabetes as part of a checkup. A urinalysis is done to see how much protein is in the urine. That is the main sign someone has diabetic nephropathy.
Some laboratory tests for diabetic nephropathy and kidney failure are:
- BUN (blood urea nitrogen — BUN is what forms when protein breaks down)
- Serum creatinine (measures creatinine in blood)
- 24-hour urine protein (measures amount of protein in urine)
- Blood levels of phosphorus, calcium, bicarbonate and potassium
- Protein electrophoresis (measures different types of protein in the urine)
- Red blood cell (RBC) count
If a patient with diabetes has a consistent amount of protein in their urine, has diabetic retinopathy (eye disease) and does not have any other kidney or renal tract disease, a doctor may be able to diagnose the disease by doing a kidney biopsy.
Who should be tested for diabetic nephropathy?
According to the U.S. National Library of Medicine, the following is a list of people who should be tested for diabetic nephropathy:
- Those with type 1 diabetes generally should be tested once a year after having diabetes for 5 years
- Children with diabetes generally should be tested when they begin puberty
- Those with type 2 diabetes generally should be tested when diagnosed for the disease and once a year after that
This does not mean testing for diabetic nephropathy is limited to these individuals. If a doctor believes a patient has diabetic nephropathy, he or she will perform a urinalysis. Because chronic kidney disease progresses over time, the sooner it is caught, the more steps can be taken to help slow the progression of kidney damage.
Blood pressure and diabetic nephropathy
A person can have high blood pressure in addition to diabetic nephropathy. Because kidney damage can affect blood pressure and high blood pressure can cause more damage to the kidneys; blood pressure can be hard to control. The National Diabetes Information Clearinghouse (NDIC) states:
- Blood pressure control reduces the risk of cardiovascular disease — heart disease or stroke — among persons with diabetes by 33 to 50 percent, and the risk of microvascular complications — eye, kidney and nerve diseases — by approximately 33 percent.
- In general, for every 10 mm Hg reduction in systolic blood pressure, the risk for any complication related to diabetes is reduced by 12 percent.
If you have high blood pressure, your doctor will prescribe medicines to help keep blood pressure in an optimal range. You doctor may even prescribe blood pressure medicine if you do not have high blood pressure because some blood pressure lowering medicines have been shown to slow the progression of kidney disease.
Treating diabetic nephropathy
Diabetic nephropathy needs to be treated in order to help slow kidney disease and other related complications.
Monitoring blood sugar levels and keeping glucose in an optimum range is important to help control kidney disease. Kidney damage may be halted or slowed down if blood sugar is kept in good range. Be sure to test your blood sugar levels often and keep track of what you eat so you know what is making your sugar level go up.
Another way to reduce the risk of more kidney damage is to keep blood pressure in check (under 130/80). Blood pressure medicine, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), may be prescribed by a doctor.
Here are some other recommended ways to help treat diabetic nephropathy and slow kidney damage:
- Keep cholesterol level under control
- Eat a low-fat diet
- Exercise regularly
- Work with a renal dietitian
- Limit protein to a healthy level determined by your doctor or dietitian
- Limit sodium intake
- Don’t smoke or use tobacco products
For those with diabetes and kidney disease, maintaining a healthy heart is important. Those with diabetes are 2 to 4 times likelier to die of heart or blood vessel disease. Kidney disease patients are at an even greater risk of getting heart disease.
Low protein diets have been promoted for people with chronic kidney disease to decrease the kidney’s workload and perhaps delay progression of kidney failure. People with diabetes must approach protein restricted diets with caution. Having diabetic nephropathy means some protein is lost in the urine. Diabetics with poorly controlled blood sugar levels have increased protein breakdown and may need additional protein to prevent protein deficiency and muscle breakdown. Nutritional assessment by a dietitian to determine protein status and protein requirements is recommended before going on a low protein diet. Most people with diabetes need between .8 to 1.0 grams of protein per kilogram of body weight. Optimal blood sugar control is extremely important. Most people with diabetes require between 10 percent up to 20 percent of their calories from protein. The amount must be based on each person’s nutritional status, kidney function and individual needs.
The recommended way to help prevent diabetic nephropathy is to keep blood sugar under control. A healthy diet, regular exercise and taking the medicines prescribed by your doctor can also help prevent kidney disease. If you have diabetes and go to your yearly checkup, be sure that your doctor tests blood and urine for signs of kidney problems. The earlier diabetic nephropathy is detected, the better chances a person can treat and maintain his or her kidney function.
- Diabetic nephropathy — Medline Plus
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