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July 12, 2013
Dear Mayo Clinic:
My father was recently diagnosed with diabetic kidney disease. Is there a chance this can be reversed, or will he have it for life? What changes, if any, should he be making to his diet?
It is not uncommon for people who have diabetes to develop kidney problems. When diagnosed early, it may be possible to stop diabetic kidney disease and fix the damage. If the disease continues, however, the damage may not be reversible.
Diabetic kidney disease, also called diabetic nephropathy, happens when diabetes damages blood vessels and other cells in the kidneys. This makes it hard for them to work as they should. In the early stages, diabetic kidney disease has no symptoms. That's why it is so important for people with diabetes to regularly have tests that check kidney function.
In later stages of the disease, as kidney damage gets worse, signs and symptoms do appear. They may include ankle swelling, test findings that show protein in the urine, and high blood pressure. Over time, diabetic kidney disease can lead to end-stage kidney disease.
If your father is in the early stages of diabetic kidney disease, there are several steps he can take to help protect his kidneys. First, it is critical to keep blood sugar as well controlled as possible. This not only helps the kidneys, but decreases the risk of other serious problems that can come from diabetes, such as blindness, heart attack and damage to the blood vessels and nerves.
Keeping blood pressure under control also is important. High blood pressure can speed up the process of diabetic kidney disease and make kidney damage worse. In general, blood pressure of 140/90 in the doctor's office and 135/85 at home is a good goal. But your father should check with his doctor to find out what's appropriate for him.
Eating a diet low in salt, quitting smoking, and limiting alcohol can all lower blood pressure. In addition to these lifestyle changes, medication to control blood pressure may be useful. The most common blood pressure medications for people with diabetes are angiotensin converting enzyme, or ACE, inhibitors and angiotensin receptor blockers, or ARBs.
Healthy cholesterol levels can help kidney function, too. Typical recommendations include keeping the level of "bad" cholesterol — called low density lipoprotein cholesterol, or LDL — to less than 100 milligrams (mg) of cholesterol per deciliter (dL) of blood. An ideal level for someone with diabetes is 80 mg/dL.
Diet has a direct impact on cholesterol. A diet rich in fiber, vegetables, fruits, heart-healthy fish and whole grains that is also low in fat and dietary cholesterol can go a long way toward lowering LDL cholesterol. Eating a healthy diet can also help shed extra pounds. That's good for the kidneys because being at a healthy weight helps keep blood sugar, blood pressure and cholesterol levels down.
In addition, your father needs to be careful when taking medications. He should not take over-the-counter medications that belong to the group of drugs known as nonsteroidal anti-inflammatory drugs, or NSAIDs. These include ibuprofen and naproxen. Some prescription medications may lead to kidney damage, too. If a doctor recommends a new medication to him, your father should ask about the possible impact on his kidney disease. Some medications may need to be avoided completely. But many more simply need the dose adjusted to fit his kidney function.
If he needs medical imaging tests that normally use dye, such as CT scans, your father should remind his health care providers that he has diabetic kidney disease. Because these dyes may lead to kidney damage in people with kidney disease, it is generally recommended they avoid them.
Finally, to monitor his condition and to help protect his kidneys' long-term health, encourage your father to see a nephrologist regularly.
— John Graves, M.D., Nephrology/Hypertension, Mayo Clinic, Rochester, Minn.