Nephropathy is the term used when the kidneys start to incur damage, which can ultimately lead to kidney failure. In this article, we look at the link between diabetes and kidney failure.
What is diabetic nephropathy?
A diagram of diabetic nephropathy in the left kidney.
Kidney problems are relatively common in people with diabetes. This is because diabetes affects the arteries in the body and the kidney filters blood from those arteries. It is estimated that around 40 percent of people who have type 2 diabetes develop nephropathy.
People with either type 1 or type 2 diabetes can be affected by nephropathy. Diabetic nephropathy is a significant cause of long-term kidney disease and end-stage renal disease (ESRD), which is when the kidneys no longer work well enough to meet the needs of daily life.
There are five stages of diabetic nephropathy, and ESRD is the last. Diabetic nephropathy is the most frequent cause of ESRD in the United States, with between 40 and 50 percent of all ESRD cases directly related to it. A person with ESRD will require dialysis.
Diabetic nephropathy is when the kidneys become leaky, allowing albumin (a protein made by the liver) to pass into the urine. The condition worsens as the level of albumin increases.
Diabetic nephropathy develops slowly and is more common in people who have had diabetes for 20 years or more.
Diabetic nephropathy is more likely to develop in people with diabetes who also have higher blood glucose levels. Doctors also believe that nephropathy is directly influenced by high blood pressure (hypertension), which may make an individual go through the stages of diabetic nephropathy more rapidly.
Other risk factors for diabetic nephropathy include:
- age, as it is more common in older people
- sex, as it is more common in men
- race, as it is more common in African Americans and Mexican Americans
Symptoms and stages
Symptoms of stage four or five diabetic nephropathy may include shortness of breath, swollen ankles, and darker urine.
Although diabetic nephropathy means the kidneys are not functioning properly, a person in the early stages may not experience any symptoms.
However, in the early stages, there are changes in blood pressure and the fluid balance in the body. Over time, this can produce a buildup of waste products in the blood and make a person very ill.
Severe illness usually occurs around stage four or five of diabetic nephropathy. Symptoms include:
- swollen ankles, feet, lower legs, or hands caused by water retention
- darker urine, due to blood in the urine
- shortness of breath
- fatigue, caused by lack of oxygen in the blood
- nausea or vomiting
- metallic taste
The stages of diabetic nephropathy are determined by the extent of the kidney damage and the glomerular filtration rate, or GFR. The GFR can tell a doctor how well the kidneys are working. A low GFR indicates kidney problems.
- Stage 1: Kidney damage present but normal kidney function; GFR above 90.
- Stage 2: Kidney damage with some loss of kidney function; GFR between 60 and 89.
- Stage 3: Mild to severe loss of kidney function; GFR between 30 and 59.
- Stage 4: Severe loss of kidney function; GFR between 15 and 29.
- Stage 5: Kidney failure; GFR less than 15.
Early treatment can delay or prevent the onset of diabetic nephropathy. As the early stages can often show no symptoms, people with diabetes should be screened for kidney complications yearly.
Screening involves a simple urine test to see whether proteins are present in the urine. However, the presence of proteins does not necessarily mean a person has kidney disease, as they can also be due to a urinary tract infection.
The primary purpose of treatment is to maintain and control blood glucose levels and blood pressure. Sometimes, this may involve the use of medication.
Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) have been shown to help lower blood pressure, as well as protect kidney function and prevent further damage.
Some new diabetic medications, including sodium-glucose cotransporter inhibitors (SGLT-2 inhibitors) and glucagon-like peptide (GLP)-1 agonists, may also protect the kidneys.
If diabetic nephropathy has developed to the final stage and ESRD then there are only two types of treatment available, kidney dialysis and kidney transplant.
If diabetic nephropathy develops to the final stage, then kidney dialysis may be used as a treatment option.
Kidney dialysis is a procedure during which waste products are separated from the blood and removed from the body. Dialysis acts as a substitute for a healthy kidney.
A person who requires kidney dialysis will usually have to undergo the treatment for the rest of their life or until a kidney transplant is available.
There are three types of dialysis:
- Haemodialysis, where blood is taken from a blood vessel in the forearm and filtered by a dialysis machine. Sessions take around 4 hours and are usually carried out 3 times a week.
- Continuous ambulatory peritoneal dialysis, where dialysis fluid is delivered into the abdomen through a catheter. Fluid stays inside for several hours to filter waste products and is drained afterward, which takes 30 to 40 minutes.
- Automated peritoneal dialysis, where a person is connected to a dialysis machine for 8 to 10 hours overnight while they sleep. The machine controls the drainage of the fluid.
A doctor may recommend a kidney transplant if diabetic nephropathy has reached the final stages. A kidney transplant requires an available donor, however, which can take some time.
People can survive with one working kidney, so a donor is an option for some people. However, the body receiving the kidney may still reject the new organ. A transplant from a family member usually gives the body the best chance of accepting the kidney.
Surgery for a kidney transplant is done using a general anesthetic and takes about 3 to 4 hours. Around 20 percent of transplanted kidneys are rejected by the recipient's body.
People with diabetes should work to keep their blood glucose levels under control to reduce their chance of developing diabetic nephropathy. It is also vital to keep blood pressure at a healthy level.
There are many lifestyle changes that people can make to help control glucose levels and blood pressure, including:
- eating a nutritious diet low in carbohydrates and other sugars
- exercising regularly
- avoiding alcohol and tobacco
- checking blood glucose levels regularly
The outlook for people with diabetic nephropathy will depend on the stage of their condition. The earlier treatment starts, the better the outlook.
If diabetic nephropathy develops into ESRD, it can lead to some serious illnesses, such as kidney failure or cardiovascular diseases. Cardiovascular disease is one of the primary causes of death in people with kidney disease and those with diabetes.
Proper treatment can delay or prevent the development of diabetic nephropathy. People with diabetes should take early steps to prevent the condition, as it can take 20 years for diabetic nephropathy to reach its final stages.