Diabetic nephropathy is a kind of chronic kidney disease (CDK). The kidneys help regulate the levels of fluids and salts in the body, which is vital for controlling blood pressure and protecting cardiovascular health.
When a person has diabetes, whether type 1, type 2, or gestational diabetes, their body cannot use or produce insulin as it should. Gestational diabetes occurs during pregnancy and may increase the risk of type 2 diabetes later in life.
Diabetes results in high blood sugar levels. Over time, these high glucose levels can damage various areas of the body, including the cardiovascular system and kidneys. The kidney damage that results is known as diabetic nephropathy.
Diabetic nephropathy is a major cause of long-term kidney disease and end-stage renal disease (ESRD). In ESRD, the kidneys no longer work well enough to meet the needs of daily life. ESRD can lead to kidney failure with potentially life-threatening consequences.
This article looks at how diabetes can affect the kidneys, the treatment available, and how to reduce the risk.
Learn more about type 1 and type 2 diabetes.
What is diabetic nephropathy?
Diabetic nephropathy is a possible complication of diabetes.
Nephropathy can affect people with any type of diabetes because it results from damage due to high blood glucose.
High blood glucose levels affect the arteries in the body, and the kidneys filter blood from those arteries.
Authors of a study from 2016 note that 20–40% of people with diabetes develop some kind of kidney disease.
Tests may show that a person has one or both of the following:
High levels of albumin in the urine: When the kidneys are healthy, the urine should contain none of the protein known as albumin.
A low glomerular filtration rate (GFR): A key function of the kidneys is to filter the blood. Kidney damage affects their ability to do this. Ideally, the kidneys should function at 100%, or have a GFR of 100. If tests show that the GFR is 60% or above, a doctor will not diagnose kidney disease. From 15–60%, there is kidney disease. Below 15% indicates kidney failure.
ESRD is the last stage of kidney disease. Diabetic nephropathy is the most frequent cause of ESRD in the United States. Some 40–50% of all cases of ESRD relate to diabetes. A person with ESRD will require dialysis.
Managing blood sugar levels can reduce the risk. Whether a person has type 1 or type 2 diabetes, they can reduce the risk of diabetic nephropathy by:
- monitoring blood glucose levels and keeping them within the target range
- having a healthful diet that is low in sugar and salt
- getting regular exercise
- following a treatment plan, which may include the use of insulin or other medications
- maintaining a healthy weight
What is chronic kidney disease? Find out more here.
Damage to the kidneys puts stress on these vital organs and prevents them from working properly.
When this happens:
- the body starts to lose protein through the urine
- the kidneys cannot remove waste products from the blood
- the kidneys cannot maintain healthy fluid levels in the body
Diabetic nephropathy develops slowly. According to one study, a third of people show high levels of albumin in their urine 15 years after a diagnosis of diabetes. However, fewer than half of these people will develop full nephropathy.
Statistics have suggested that kidney disease is uncommon in people who have had diabetes for less than 10 years. Also, if a person has no clinical signs of nephropathy 20–25 years after diabetes starts, they have a low chance of developing it thereafter.
Diabetic nephropathy is less likely if a person with diabetes manages their glucose levels effectively.
Other risk factors
Other risk factors include:
Smoking: Kidney damage may result from a link between smoking and higher levels of inflammation. While the link between smoking and diabetes remains unclear, there appears to be a greater incidence of diabetes, as well as hypertension and kidney disease, among people who smoke.
Age: Kidney disease, and especially a low GFR is more common in people aged 65 years and above.
Sex: The condition is more common in men than in women.
Race, ethnicity, or both: It is more common in African Americans, Native Americans, and Asian Americans.
Some of these risks either are or appear to be contributing factors to or complications of diabetes.
Symptoms and stages
In the early stages of diabetic nephropathy, a person may not notice any symptoms. However, changes in blood pressure and the fluid balance in the body may already be present. Over time, waste products can build up in the blood, leading to symptoms.
A doctor may break down the stages of kidney disease, depending on the GFR, which also represents the percentage of effective kidney function.
Stage 1: Kidney damage present but normal kidney function and a GFR of 90% or above.
Stage 2: Kidney damage with some loss of function and a GFR of 60–89%.
Stage 3: Mild to severe loss of function and a GFR of 30–59%.
Stage 4: Severe loss of function and GFR of 15–29%.
Stage 5: Kidney failure and a GFR of under 15%.
At stage 4 or 5, symptoms such as dark urine may be noticable.
In the early stages, a person may not notice any symptoms. At stage 4 or 5, they may feel unwell and experience the following symptoms:
- swollen ankles, feet, lower legs, or hands due to water retention
- darker urine due to blood in the urine
- shortness of breath
- fatigue due to lack of oxygen in the blood
- nausea or vomiting
- a metallic taste in the mouth
Complications of late-stage kidney disease include cardiovascular disease.
Following a treatment plan for diabetes and attending regular health checks can help a person with diabetes control their blood sugar levels, reduce the risk of kidney problems, and find out early if they need to take action.
Screening involves a person taking a urine test to check for proteins in the urine. However, having proteins in the urine does not necessarily indicate kidney disease, as it could also be due to a urinary tract infection.
Early treatment can delay or prevent the onset of diabetic nephropathy.
The main aim of treatment is to maintain and control blood glucose levels and blood pressure. This may involve the use of medication.
Angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) can help lower blood pressure, protect kidney function, and prevent further damage.
In 2018, the American College of Cardiology issued guidelines recommending the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors or glucagon-like peptide-1 receptor agonists (GLP-1RAs) for people with type 2 diabetes and CKD. These drugs may reduce the risk of CDK progression, cardiovascular events, or both.
If a person has kidney disease, their doctor may ask them to keep track of the following nutrients:
Water: Although essential, too much water or fluid may increase the risk of swelling and high blood pressure
Sodium: This can raise blood pressure as it is a constituent of salt.
Protein: For a person with kidney disease, protein can cause waste to build up in the blood, putting extra pressure on the kidneys.
Phosphorus: This occurs in many protein and dairy foods. Too much phosphorus can weaken the bones and put pressure on the kidneys.
Potassium: People with kidney disease can have higher levels of potassium than is healthful, which can affect nerve cells.
Click here to learn more about the high potassium foods a person should avoid if they have kidney disease.
Managing blood sugar levels
This is crucial for lowering the risk of diabetes complications, such as kidney disease, cardiovascular disease, and diabetic neuropathy, which affects the nervous system.
These conditions, too, can lead to further complications. Managing blood sugar levels can also help prevent these from developing.
Late-stage treatment options
If diabetic nephropathy progresses to ESRD, a person will need either dialysis or a kidney transplant. They will usually need dialysis for the rest of their life or until a kidney transplant is available.
If the kidneys stop working effectively, dialysis may be necessary.
Kidney dialysis is a procedure that typically uses a machine to separate waste products from the blood and remove them from the body. Dialysis acts as a substitute for a healthy kidney.
There are different types of dialysis:
Hemodialysis: Blood leaves the body through a needle in the forearm and passes through a tube to a dialysis machine. The machine filters the blood outside the body, and the blood returns through another tube and needle.
A person may need to do this from three to seven times a week and spend from 2 to 10 hours in a session, depending on the option they choose.
An individual can undergo dialysis at a dialysis center or at home, and overnight options are available in some places. Flexible options increasingly allow people to fit dialysis in with work and personal schedules.
Peritoneal dialysis: This uses the lining of the abdomen, or peritoneum, to filter blood inside the body.
- In continuous ambulatory peritoneal dialysis (CAPD), dialysis fluid enters the abdomen through a catheter. The fluid stays inside for several hours, filtering waste products before draining out. Draining takes 30–40 minutes.
- In continuous cycler-assisted peritoneal dialysis (CCPD), or automated peritoneal dialysis, a person spends 8–10 hours overnight connected to a dialysis machine, while they sleep. The machine controls the drainage of the fluid.
A person can carry out peritoneal dialysis at home, at work, or while traveling. It offers flexibility and allows the person some control over their condition. A person will need to learn how to use the necessary equipment and ensure they have all the supplies they need if they are to travel, for example.
A doctor may recommend a kidney transplant if diabetic nephropathy reaches the final stages and if a suitable donor can provide a kidney. Finding a donor may take some time.
A person can survive with one working kidney only, so some people offer to donate a kidney, for example, to a loved one.
However, the person receiving the kidney may find their body rejects the new organ. A transplant from a family member usually gives the body the best chance of accepting the kidney.
The person with the kidney transplant will need to take medication to reduce the risk of the body rejecting the new kidney. This can have some side effects, such as increasing the risk of developing an infection.
Financial help is available for many people. Medicare and Medicaid usually cover treatment for kidney failure, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
A person can get Medicare for ESRD at any age if all of the following apply:
- Their kidneys no longer work.
- They need regular dialysis or have undergone a kidney transplant.
- They have worked the necessary time under Social Security, the Railroad Retirement Board, or as a government employee.
- They are already getting or are eligible for Social Security or Railroad Retirement benefits.
- They are the spouse or dependent child of someone who meets either of the above requirements.
The individual should speak to their insurance provider or their doctor about the options.
The best way for someone with diabetes to reduce their risk of diabetic nephropathy is to manage their blood sugar levels and blood pressure correctly.
Lifestyle changes that can help with this include:
- eating a nutritious diet that is high in fiber and low in sugar, processed carbohydrates, and salt
- exercising regularly
- limiting alcohol intake
- avoiding tobacco
- checking blood glucose levels regularly
- following any treatment plan their doctor suggests
- limiting stress where possible
Learning as much as a person is able about diabetes and its complications, including kidney disease, can help them feel more confident and more in control over their condition and ways of preventing it.
The NIDDK's National Kidney Disease Education Program provides a downloadable record of test results that can help a person keep track of their kidney tests and progress.
The outlook for people with diabetic nephropathy will depend on how well they manage their blood sugar and blood pressure levels and the stage at which they receive a diagnosis. The earlier treatment starts, the better the outlook.
Treatment can delay or prevent the progress of diabetic nephropathy. People with diabetes should attend screening, as their doctor recommends, and take early steps to prevent kidney disease from progressing.
Learn more here about how the kidneys work.
Is it possible to reverse kidney damage once it starts?
Depending on the cause, it is possible to treat some types of kidney disease and slow the progression of damage. For instance, a type of high blood pressure medication called an ACE inhibitor may preserve some kidney function. Certain dietary choices may reduce the work your kidneys must do. Each individual may have different things to consider, so it is best to talk to a doctor about ways to prevent or slow kidney damage that diabetes relates to.Deborah Weatherspoon, PhD, RN, CRNA Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.