Kidney Disease of Diabetes

Each year in the United States, more than 50,000 people are diagnosed with end stage renal disease (ESRD), a serious condition in which the kidneys fail to rid the body of wastes ESRD is the final stage of a slow deterioration of the kidneys, a process known as nephropathy.

Diabetes is the most common cause of ESRD, resulting in about one-third of new ESRD cases. Even when drugs and diet are able to control diabetes, the disease can lead to nephropathy and ESRD. Most people with diabetes do not develop nephropathy that is severe enough to cause ESRD. About 15 million people in the United States have diabetes, and about 50,000 people have ESRD as a result of diabetes.

ESRD patients undergo either dialysis, which substitutes for some of the filtering functions of the kidneys, or transplantation to receive a healthy donor kidney. Most U.S. citizens who develop ESRD are eligible for federally funded care. In 1994, the Federal Government spent about $9.3 billion on care for patients with ESRD.

African Americans and Native Americans develop diabetes nephropathy, and ESRD at rates higher than average Scientists have not been able to explain these higher rates. Nor can they explain fully the interplay of factors leading to diabetic nephropathy – factors including heredity, diet, and other medical conditions, such as high blood pressure. They have found that high blood pressure and high levels of blood sugar increase the risk that a person with diabetes will progress to ESRD.

Two types of diabetes

In diabetes – also called diabetes mellitus, or DM – the body does not properly process and use certain foods, especially carbohydrates. The human body normally converts carbohydrates to glucose, the simple sugar that is the main source of energy for the body’s cells. To enter cells, glucose needs the help of insulin, a hormone produced by the pancreas. When a person does not make enough insulin, or the body is unable to use the insulin that is present, the body cannot process glucose, and it builds up in the bloodstream. High levels of glucose in the blood or urine lead to a diagnosis of diabetes.

NIDDM

Most people with diabetes have a form known as noninsulin dependent diabetes (NIDDM), or Type II diabetes. Many people with NIDDM do not respond normally to their own or to injected insulin – a condition called insulin resistance NIDDM occurs more often in people over the age of 40, and many people with NIDDM are overweight. Many also are not aware that they have the disease. Some people with NIDDM control their blood sugar with diet and an exercise program leading to weight loss. Others must take pills that stimulate production of insulin: still others require injections of insulin.

IDDM

A less common form of diabetes, known as insulin-dependent diabetes (IDDM), or Type I diabetes, tends to occur in young adults and children. In cases of IDDM, the body produces little or no insulin. People with IDDM must receive daily insulin injections.

NIDDM accounts for about 95 percent of all cases of diabetes. IDDM accounts for about 5 percent. Both types of diabetes can lead to kidney disease. IDDM is more likely to lead to ESRD. About 40 percent of people with IDDM develop severe kidney disease and ESRD by the age of 50. Some develop ESRD before the age of 30. NIDDM causes 80 percent of the ESRD in African Americans and Native Americans.

Effect of high blood pressure

High blood pressure, or hypertension, is a 2 major factor in the development of kidney problems in people with diabetes. Both a family history of hypertension and the presence of hypertension appear to increase chances of developing kidney disease. Hypertension also accelerates the progress of kidney disease where it already 140 millimeters of mercury systolic and 90 millimeters of mercury-diastolic. Professionals shorten the name of this limit to “140 over 90.’’ The terms systolic and diastolic refer to pressure in the arteries during contraction of the heart (systolic) and between heartbeats (diastolic).

Hypertension can be seen not only as a cause of kidney disease, but also as a result of damage created by the disease. As kidney disease proceeds, physical changes in the kidneys lead to increased blood pressure. Therefore, a dangerous spiral involving rising blood pressure and factors that raise blood pressure, occurs. Early detection and treatment of even mild hypertension are essential for people with diabetes.

Preventing and slowing kidney disease

Blood pressure medicines
Scientists have made great progress in developing methods that slow the onset and progression of kidney disease in people with diabetes. Drugs used to lower blood pressure (antihypertensive drugs) can slow the progression of kidney disease significantly. One drug, an angiotensin-converting enzyme (ACE) inhibitor, has proven effective in preventing progression to stage IV and V*. Calcium channel blockers, another class of antihypertensive drugs, also show promise.

An example of an effective ACE inhibitor is captopril which the Food and Drug Administration approved for treating kidney disease of Type I diabetes. The benefits of captopril extend beyond its ability to lower blood pressure; it may directly protect the kidney’s glomeruli. ACE inhibitors have lowered proteinuria and slowed deterioration even in diabetic patients who did not have high blood pressure.

Some, but not all, calcium channel blockers may be able to decrease Proteinuria and damage to kidney tissue. Researchers are investigating whether combinations of calcium channel blockers and ACE inhibitors might be more effective than either treatment used alone Patients with even mild hypertension or persistent microalbuminuria should consul a physician about the use of antihypertensive medicines.

Low-Protein diets

A diet containing reduced amounts of protein may benefit people with kidney disease of diabetes. In people with diabetes excessive consumption of protein may be harmful Experts recommend that most patients with stage III or stage IV nephropathy consume moderate amounts of protein.

Intensive management

Antihypertensive drugs and low protein diets can slow kidney disease when significant nephropathy is present, as in stages III and IV. A third treatment known as intensive management of schemic control, has shown great promise for people with IDDM, especially for those with early stages of nephropathy.

Good Care Makes a Difference

If you have diabetes

• Ask your doctor about the DCCT and how its results might help you.
• Have your doctor measure your glycohemoglobin regularly. The HbA1c test averages your level of blood sugar for the previous 1-3 months.
• Follow your doctor’s advice regarding insulin injections, medicines, diet, exercise, and monitoring your blood sugar.
• Have your blood pressure checked several times a year. If blood pressure is high, follow your doctor’s plan for keeping it near normal levels.
• Ask your doctor whether you might benefit from receiving an ACE inhibitor.
• Have your urine checked yearly for microalbumin and protein. If there is protein in your urine, have your blood checked for elevated amounts of waste products such as creatinine.
• Ask your doctor whether you should reduce the amount of protein in your diet.

Intensive management is a treatment regimen that aims to keep blood glucose levels close to normal. The regimen includes frequently testing blood sugar, administering insulin on the basis of food intake and exercise, following a diet and exercise plan, and frequently consulting a health care team.

A number of studies have pointed to the beneficial effects at intensive management. Two such studies, funded by the National Institute of Diabetes and Digestive and Kidney Disease (NIDDR) of the National Institutes of Health, are the Diabetes Control and Complications Trial (DCCT)* and a trial led by researchers at the University of Minnesota Medical School.**

The DCCT. Conducted from 1983 to 1993, involved 1,441 participants who had IDDM. Researchers found a 50 percent decrease in both development and progression of early diabetes kidney disease (stages I and II) in participants who followed an intensive regimen for controlling blood sugar levels. The intensively managed patients had average blood sugar levels of 150 milligrams per deciliter – about 80 milligrams per deciliter lower than the levels observed in the conventionally managed patients.

In the Minnesota Medical School trial, researchers examined kidney tissues of long-term diabetics who received healthy kidney transplants. After 5 years, patients who followed an intensive regimen developed significantly fewer lesions in their glomeruli than did patients not following an intensive regimen. This result along with findings of the DCCT and studies performed in Scandinavia, suggests that any program resulting in sustained lowering of blood glucose levels will be beneficial [-] patients in the early stages of diabetic nephropathy.

Dialysis and transplantation

When people with diabetes reach ESRD, they must undergo either dialysis or a kidney transplant. As recently as the 1970s, medical experts commonly excluded people with diabetes from dialysis and transplantation in part because the experts felt damage caused by diabetes would offset benefits of the treatments. Today because of better control of diabetes and improved rates of survival following treatment doctors do not hesitate to offer dialysis and kidney transplantation to people with diabetes.

Currently, the survival of kidneys transplanted into diabetes patients is about the same as survival of transplants in people without diabetes Dialysis for people with diabetes also works well in the short run. Even so. People with diabetes who receive transplants or dialysis experience higher morbidity and mortality because of coexisting complications of the diabetes – such as damage to the heart eyes and nerves.

Looking to the future

The incidences of both diabetes and ESRD caused by diabetes have been rising. Some experts predict that diabetes soon might account for half the cases of ESRD. In light of the increasing morbidity and mortality related to diabetes and ESRD. Patients. Researchers, and health care professionals will continue to benefit by addressing the relationship between the two diseases. The NIDDK is a leader in supporting research in this area.

Several areas of research supported by NIDDK hold great potential Discovery of ways to predict who will develop kidney disease may lead to greater prevention as people with diabetes why learn they are at risk institute strategies such as intensive management and blood pressure control Discovery of better anti-rejection drugs will improve results of kidney transplantation in patients with diabetes who develop ESRD for some people with IDDM advances in transplantation-expecially transplantation of insulin producing cells of the pancreas- could lead to a cure for both diabetes and the kidney disease of diabetes.

Kidney Function

The body normally has two kidneys. They are located near the back on each side of the spine. These organs do many jobs. One is the cleaning (filtering) of the blood, removing waste products and excess fluids. This waste is called urine. The urine travels out of the kidneys through the ureters. From the ureteres the urine goes into the bladder where it is stored until it is released through the urethra and out of the body.

Other important jobs of the kidneys include the making of substances which affect the blood pressure, the production of red blood cells, the use of vitamin D, and the production and changing of sex hormones.

The body can work well without one kidney. It isn’t until more than three-quarters of the kidneys are damaged that problems even show up. For that reason patients often don’t feel sick when injury is first happening to their kidneys.

As damage to the kidneys worsens excess water remains in the body. Swelling of the legs occurs. This is called edema. So much water may build up that it can flood the lungs. As a result the person feels short of breath, has trouble lying flat in bed without propping the head on two or three pillows, or awakens at night and must sit up to breath.

In addition to the water, other waste products also build up. These include potassium, acid and phosphorus. When there are too many of these elements in the blood the person usually feels ill and experiences nausea, vomiting, or diarrhea.

High blood pressure, anemia (low blood count), and hormone imbalance also are the result of kidney damage.