Diabetic nephropathy
Diabetic nephropathy refers to kidney problems which result from diabetes mellitus. These include the excretion of protein in the urine (proteinuria) and slowly developing kidney failure.
What do the kidneys do?
Kidneys take waste products and excess water from the bloodstream so that they can be expelled from the body in the form of urine. This is carried out by a system of tubes and blood vessels known as nephrons. Inside the nephrons are tiny blood vessels called capillaries and tiny urine-collecting tubes. One of the major structures in the nephron is a group of blood vessels known as the glomerular tuft (or glomerulus). It acts as a filter.
What happens to the kidneys in diabetes?
Diabetes interferes with the function of the glomerular tuft. When enough of these tufts have been affected, kidney failure results. Many people with diabetes have some degree of kidney failure, whereby the filtering function of the kidneys doesn't work properly and proteins are lost from the body in the urine.
This is why your doctor may test your urine to see if there is protein present. When the glomerular filters are first damaged by diabetes, a very small amount of protein can leak into the urine from the bloodstream. The protein is called albumin, and its presence in the urine is called microalbuminuria.
Sometimes the damage is severe enough that the kidneys are not capable of doing their cleaning/filtration job and this will have to be done by dialysis, or even by a new kidney via a kidney transplant.
Symptoms of diabetic nephropathy
In diabetic nephropathy, symptoms typically are not evident for many years, until kidney function has deteriorated significantly. The development of diabetic nephropathy can take about 10 to 20 years from initial disease to end-stage kidney (renal) disease.
However, there are signs that your doctor may be able to test for which indicate that nephropathy is developing, for example regularly testing your urine for microalbuminuria.
Proteinuria
Most people with established diabetic nephropathy have urine containing large quantities of protein (known as proteinuria), which their doctors can detect using a dipstick urine test. These people may need to consume a low-protein diet. However, not all diabetic people with this problem will go on to develop kidney failure.
High blood pressure
Another related condition of diabetic nephropathy is high blood pressure (hypertension). Hypertension will speed up existing kidney disease, so treatment of even mild hypertension is necessary for those with diabetes. Because the function of the kidney deteriorates and protein is lost, puffy swelling of the body tissues, especially the legs, can occur. This is called the nephrotic syndrome.
Your doctor may prescribe medication to lower blood pressure, which has been shown to help in diabetic nephropathy.
Who gets diabetic nephropathy?
Nephropathy is generally seen in middle-aged or older people who have had diabetes for at least 10 years. About 20 to 30 per cent of people with diabetes will develop nephropathy. People with type 1 diabetes have a slightly higher risk of developing diabetic nephropathy than those with type 2 diabetes.
People with nephropathy may already have other complications of diabetes, such as retinopathy (damage to the retina of the eye), neuropathy (damage to nerves), and problems with the circulatory system.
What can you do?
As previously mentioned, your doctor may prescribe blood pressure medication to help your condition.
You may be advised to follow a diet incorporating reduced amounts of protein.
Studies have shown that tight control of blood sugar to keep it at normal levels has benefited those with diabetic nephropathy, especially in the early stages. Your doctor may recommend a programme where you test your blood sugar often and adhere to a strict diet and exercise regimen and keep records of all your measurements and activities.
Outlook
Diabetic nephropathy is the most common cause of end-stage renal disease, which may account for up to 25 per cent of all deaths in people with diabetes. However, advances in treatment options such as kidney transplants are being made all the time.
Recent research has shown that strict control of risk factors for diabetic nephropathy such as high blood pressure and high blood sugar can not only stop the progression of kidney disease in people with diabetes, but during the early stages it can actually reverse it.
Last Reviewed: 07 September 2009
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