About 30–40 percent of people with type 1 diabetes and 20 percent of those with type 2 diabetes eventually develop kidney damage that can lead to kidney failure. The damage occurs in tiny blood vessels (called capillaries) throughout the kidneys, which act as filters to remove waste products from the bloodstream. The risk of heart attack and stroke is also increased in people with kidney damage.
The first detectable sign of kidney damage is the appearance of small amounts of a protein called albumin in the urine (microalbuminuria), which usually develops after you have had diabetes for five to 10 years. Over the next eight to 10 years, worsening of kidney damage may cause leakage of larger quantities of protein into the urine (proteinuria), accumulation of waste products in the blood (azotemia), and finally kidney failure, which requires treatment with dialysis or a kidney transplant.
Prevention and treatment of kidney damage
Four strategies are used to prevent and slow the progression of kidney damage. The first three are: tight glucose control, treating high blood pressure, and restricting protein in the diet. The fourth is treatment with either an ACE inhibitor or angiotensin II receptor blocker, drugs commonly prescribed for high blood pressure.
To detect kidney damage in its early stages, people with type 2 diabetes should have a urine test for microalbuminuria once a year as soon as diabetes is diagnosed. In people with type 1 diabetes, testing should start within five years of diagnosis. If the test is positive, your doctor will tell you to lower your blood glucose and blood pressure and may recommend a low-protein diet to decrease protein loss in the urine and decrease the kidneys' workload. All adults with diabetes should also undergo a serum creatinine test at least once a year to measure the filtering capacity of the kidneys.
If you have type 1 diabetes with hypertension or protein in the urine, you should take an ACE inhibitor or angiotensin II receptor blocker. Studies have shown that two ACE inhibitors, captopril (Capoten) and enalapril (Vasotec), can slow kidney damage in its early stages. ACE inhibitors decrease pressure in the small blood vessels that filter blood in the kidneys. This effect can prevent destruction of these blood vessels. Some experts recommend that people with diabetes start treatment with an ACE inhibitor at the first sign of microalbuminuria. Others believe that ACE inhibitors will delay the onset of kidney disease if they are prescribed as soon as diabetes is diagnosed. Additional studies are needed to determine which approach is more effective.
If an ACE inhibitor causes intolerable side effects—the most common is a dry cough—your doctor may prescribe an angiotensin II receptor blocker, such as irbesartan (Avapro), losartan (Cozaar), or valsartan (Diovan). Angiotensin II receptor blockers prevent the actions of angiotensin by inhibiting it from binding to receptors. These drugs are effective in protecting the kidneys from further damage and in controlling blood pressure.
Many medications you take are excreted from the body via the kidneys. So if your kidneys are failing, the drug dosage you take must be decreased to avoid buildup to toxic levels. Many people with chronic kidney failure develop weakness and fatigue from anemia. If this happens, your doctor may prescribe erythropoietin, a hormone that stimulates the production of red blood cells.
If your kidney function deteriorates to less than 10% of normal—a condition called end-stage kidney (renal) disease—you'll need kidney dialysis or a kidney transplant. One type of dialysis, hemodialysis, does the work your kidneys can no longer do by passing your blood through a machine that filters out waste products and then returns the cleaned blood to your bloodstream. Hemodialysis is performed in special treatment centers and usually requires three weekly sessions of three to five hours each.
Another procedure called peritoneal dialysis requires surgical implantation of a catheter in your abdomen through which dialysis solution (called dialysate) is delivered. The solution passes through the lining of your abdomen (the peritoneal membrane), which filters out wastes and excess fluid from the blood. The fluid is then drained out through the catheter and discarded. The process requires about half an hour every day, but you can do it yourself at home or almost anywhere. Peritoneal dialysis can also be performed with a machine called a cycler, which you can use at night while you are sleeping.
Dialysis can cause side effects, and it is time consuming and tiring. The best remedy for end-stage kidney disease is a kidney transplant. Unfortunately, many people with kidney failure must wait years until a donated kidney becomes available.