Nephropathy, or kidney disease, is among the most serious complications for many diabetics and the leading cause of kidney failure in the United States. According to the American Diabetes Association, there were more than 200,000 Americans with end-stage kidney disease living by means of dialysis in 2008. Like other diseases associated with type 2 diabetes, nephropathy has few early symptoms or warning signs. Damage to the kidneys can occur for as long as a decade before the first symptoms even appear.
According to Dr. Charles M. Clark, Jr. M.D., former chairman of the National Diabetes Education Program, “A person can have type 2 diabetes for 9 to 12 years before it’s discovered. During those years, harmful changes are already occurring, causing 5 to 10 percent to [already] have kidney disease at the time of diagnosis.”
Causes of Diabetic Nephropathy
There is no one specific cause for kidney disease, though experts believe its development is likely associated with years of uncontrolled blood glucose. Other factors likely play important roles as well, such as genetic predisposition.
The kidneys are the body’s blood filtration system. Each is made up of hundreds of thousands of nephrons that “clean” the blood of waste. Over time, especially when a person is suffering from type 2 diabetes, the kidneys become overworked because they are constantly removing excess glucose from the blood. The nephrons become inflamed and scarred (sclerosis) and they no longer work as well.
Soon, the nephrons can no longer fully filter the body’s blood supply. Material that would typically be removed from the blood, like protein, passes into the urine. Much of that unwanted material is a protein called albumin, the levels of which can be tested in a urine sample to help determine how your kidneys are functioning. A small amount of albumin in the urine is referred to as microalbuminuria; when larger amounts are found (macroalbuminuria), the dangers of kidney failure are much greater. In those cases, end-stage renal disease (ESRD) is a risk and treatment is in the form of dialysis, or having your blood filtered by machine and pumped back into your body.
Risk Factors for Diabetic Nephropathy
If you already have type 2 diabetes, or have been told you are “prediabetic” (meaning that your blood glucose is borderline high, or that you possess known factors that put you at greater risk for developing the disease), your kidneys are already overworked and their function should be tested annually. Early diagnosis of kidney disease is essential for preserving good health. Besides diabetes, other risk factors for kidney disease are:
- uncontrolled hypertension (high blood pressure)
- uncontrolled hyperglycemia (high blood glucose)
- high cholesterol
- family history of kidney disease
- family history of heart disease
- cigarette smoking
- advanced age
- race (African Americans, American Indians, Hispanic Americans, and Asian Americans show a higher prevalence of kidney disease)
Remember, there are often no symptoms of kidney disease until they are no longer functioning. Signs that your kidneys could be at risk include fluid retention and swelling in the feet, ankles, and legs, a poor appetite, feeling exhausted and weak most of the time, frequent headaches, upset stomach, nausea, and vomiting. Other signs include insomnia and difficulty concentrating.
Preventing Diabetic Nephropathy
The best way to preserve kidney health is to carefully watch your diet. Diabetics with partial kidney function need to be even more vigilant about maintaining healthy blood glucose, blood cholesterol, and lipid levels.
Maintaining a blood pressure of less than 130/80 is also essential. Even if you have mild kidney disease, it may be made much worse by hypertension. To help lower your blood pressure, eat foods low in salt, don’t add salt to meals, lose weight, and avoid alcohol. Based on your doctor’s recommendations, daily exercise is also a must. Most type 2 diabetics with hypertension take ACE inhibitors like captopril and enalapril, drugs that also have the potential to slow the progression of kidney disease. Doctors also commonly prescribe angiotensin receptor blockers, or ARBs.
If you smoke cigarettes, you should stop immediately. According to a 2011 report from the National Institute of Health, cigarette smoking is now an established risk factor for developing kidney disease.
Your doctor may also recommend medications or for you to follow a low-fat, low-protein diet.