How Diabetes Contributes to Kidney Failure

Diabetes is the most common cause of kidney failure, according to the United States Renal Data System (USRDS) 2007 Annual Data Report.

Chronic kidney disease (CKD), the precursor to kidney failure, is considered comorbid (commonly coexisting) with diabetes.

Because of the increased risk of developing kidney disease, people with diabetes should be regularly screened for any evidence that they are developing kidney issues. Evaluation generally begins five years after diagnosis of Type 1 diabetes and immediately upon diagnosis of Type 2 diabetes. After initial screening, annual screenings are recommended.

What Kidneys Do

The kidney's primary purpose is to filter impurities from the blood, which are then excreted in urine. The blood is also replenished by the kidneys, with necessary proteins and other substances added back. The kidneys release three hormones, including one that stimulates the production of red blood cells in the bone marrow and one that is the active form of vitamin D, which works in conjunction with calcium to maintain proper levels of calcium in the body. The third hormone helps to regulate blood pressure at proper levels.

How Diabetes Affects Kidneys

Diabetes has a significant impact on blood vessels, damaging the epithelial cells that line arteries, vessels and capillaries. This causes inflammation and increasing inflexibility of the vessel walls.

The filters in the kidney are made up of tiny blood vessels that are easily damaged. Accumulated damage to these vessels makes the kidneys less efficient at filtering and leads to retention of fluids and salts. This, in turn, puts more pressure on the kidneys because of the need to filter higher fluid volumes.

High sugar levels also damage the nerves in the body, which may affect the bladder. If emptying the bladder becomes a problem, the pressure of retained urine can cause a backup to the kidneys, resulting in damage.

A damaged kidney might not produce enough of the hormone that controls blood pressure. Increased blood pressure can damage the fine vessels in the kidney that provide filtering, leading to a diminished ability of the kidneys to filter impurities and create urine.

When kidneys begin to fail, dialysis is generally needed to rid the blood of impurities and to reduce the volume of fluids the kidney needs to handle.

Likelihood of Developing Chronic Kidney Disease

Not everyone with diabetes will develop either CKD or kidney failure. It generally takes at least 10 years of living with diabetes before there is any damage to the kidneys, and 15 to 25 years before kidney failure occurs. In fact, a person who has lived with diabetes for at least 25 years is unlikely to develop either CKD or kidney failure.

Why some people develop kidney problems and others don’t is unclear. Heredity, ethnic background, diet, blood pressure control and management of diabetes are all factors.

Sources: National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) and American Diabetes Association

Image credit: Abhijith Ar