In healthy kidneys, blood vessels filter waste products from the bloodstream. Injury to the vessels results in a buildup of waste in your blood. Meanwhile, proteins your body actually needs are eliminated in urine.

Kidney damage occurs in 20% to 40% of people with diabetes. If it’s untreated, it can lead to kidney failure, and perhaps the need for a kidney transplant or dialysis, which uses a special machine to filter waste products from the blood. Diabetes-related kidney disease has become the leading cause of end-stage renal (kidney) disease. And, it can increase the risk of death from heart disease.

Clues to an often “silent” problem
Kidney damage is frequently “silent”—it can sneak up on you, causing no symptoms until it reaches advanced stages. When symptoms do occur, they generally begin with fluid buildup (edema) in the legs and lungs. The excess fluid can make you gain weight and feel tired or out of breath. You may find you need to urinate more often than usual, or that your shoes and clothing feel tight. As it progresses, kidney damage can cause such symptoms as appetite loss and weight loss, nausea and vomiting, and bruising. You may also have difficulty concentrating.

Steps to prevention
But here’s the good news: Keeping watch over kidney function opens the door to many ways of preventing or slowing down kidney damage. The American Diabetes Association (ADA) recommends that people with diabetes undergo testing every year for excessive protein in the urine (proteinuria). Proteinuria is an early sign of kidney disease. The sooner kidney disease is identified, the sooner steps can be taken to prevent further damage.

People with type 1 diabetes should begin yearly testing once they’ve had diabetes for five years. But people with type 2 diabetes should be tested as soon as they are diagnosed, and every year thereafter. The urine tests are particularly important for pregnant women with diabetes.

If you have diabetes, you should be aware of several additional steps you can take to protect your kidneys.Follow instructions you’ve been given in terms of your diet and meal planning. Take prescribed drugs that are protective. Carefully control your blood glucose levels. Keep your blood pressure down. Keep regular appointments with members of your diabetes team, and be sure to ask them about any over-the-counter medicatins, herbal preparations, or vitamins you plan to take.

If you have kidney damage…
You can’t reverse kidney damage, but you may be able to slow its progress. A low-salt, low-cholesterol, and possibly low-protein diet can be helpful. You might also be prescribed medication. Two types of drugs in particular have been shown to reduce blood pressure and delay the progress of kidney damage in many people: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs).

On the other hand, frequent use of certain other medications, such as ibuprofen and naproxen, may weaken your kidneys. So, check with your diabetes care team before using these agents.

And, as always, be sure to monitor your blood glucose levels carefully and regularly—doing so may enable you to slow progression of kidney damage, especially in the early stages. If you use insulin, you may need to start taking it in smaller doses, because damaged kidneys are less able to break down insulin.