How diabetes can damage your kidneys (and what you can do about it)

Your kidneys contain millions of minute blood vessels that filter waste products from your blood. But diabetes can damage these amazing organs, so they lose their filtering ability. How is kidney disease caused and what can you do to prevent or reverse the damage?

To keep your body functioning properly, waste products and excess fluid must be removed on a regular basis.

Diagram of kidneys-ureters-bladderTo do this, you have two bean-shaped kidneys … each about the size of your fist … located on either side of your spine just below your rib cage.

Your kidneys filter and return to the bloodstream about 190 litres of blood every day. In doing so they produce up to 2 litres of urine that contain the waste products your body needs to get rid of.

The urine flows from your kidneys to your bladder. Once your bladder is full, you get an urge to pee and the urine and the wastes it contains leave your body.

Why are your kidneys vital?

But your kidneys do much more than simply remove waste products from you bloodstream … they stabilize the make-up of your blood. This is critical to keep your body functioning properly.

Specifically, your kidneys:

  • prevent the accumulation of wastes and extra fluids in your body
  • remove drugs from your body
  • stabilize the levels of the electrolytes that balance your body’s fluids

Your kidneys also make hormones that help:

  • regulate your blood pressure
  • make red blood cells
  • produce an active form of vitamin D that keeps your bones strong and healthy
How do your kidneys filter your blood?

The heart pumps about five litres of blood a minute under resting conditions. Approximately one litre (20%) enters the kidneys for filtering.

Coloured diagram of kidney filtering systemEach kidney contains about a million functioning units called nephrons. Each nephron filters a tiny amount of blood.

A nephron contains a glomerulus (which is the actual filter) and a tubule (a tiny tube). The nephron works in a two-step process.

Blood from your bloodstream enters the glomerulus. The glomerulus allows fluid and waste products to pass through but it prevents blood cells and large molecules, such as proteins, from getting through.

The filtered fluid then enters the tubule which contains a long series of ducts. In the tubule, various chemicals and water are added or removed from the filtered fluid according to your body’s needs. The fluid, containing wastes, then exits the tubule as urine and flows to the bladder.

The main substances excreted in urine are:

  • metabolic waste products ― eg urea and creatinine ― from the chemical processes (such as digestion) that keep your body functioning
  • electrolytes ― inorganic compounds (including sodium, potassium, calcium, chloride and bicarbonate) that your body uses to control its fluid content
  • water
Kidney disease

The functioning of your kidneys can deteriorate for a variety of reasons:

  • Diabetes … the leading cause of kidney disease
  • Hypertension … also a leading cause of kidney disease, as well as heart attacks and strokes
  • Glomerulonephritis … inflammation of the kidney’s tiny filtering units
  • Polycystic kidney disease … the most common inherited kidney disease
  • Kidney stones … very common and very painful
  • Urinary tract infections … most often affect the bladder but can spread to the kidneys
  • Congenital diseases … that involve some problem in the urinary tract
  • Pain relievers … long-term use of over-the-counter pain relievers
  • Recreational drugs … such as crack and heroin
  • Toxins … such as from pesticides

Uncontrolled high blood glucose and high blood pressure are, by far, the most common reasons for deterioration in kidney function.

But there are plenty of things you can do to prevent the destruction of your kidneys.

How diabetes causes kidney failure

In the first step of the filtering process, the glomerulus prevents bloods cells and large molecules (eg, proteins) from passing through to the second step.

Uncontrolled diabetes can damage this system. High levels of blood glucose make the kidneys filter too much blood. The extra work is hard on the kidneys and after years they start to leak and protein gets through into the urine.

Eventually the stress of overworking causes the kidneys to lose their filtering ability. As a result waste products start to build up in the blood. Eventually the kidneys fail and you reach end-stage renal disease (ESRD).

Uncontrolled hypertension causes chronic kidney disease in a similar manner.

How can kidney disease be detected?

Kidney disease presents few symptoms until almost all kidney functions are gone. This is because the kidneys work hard to cover for the filters that are failing.

Some of the symptoms of kidney disease are:

  • loss of sleep
  • poor appetite
  • upset stomach
  • weakness and difficulty concentrating
  • more frequent urination, especially at night
  • puffiness around the eyes, and
  • swelling of hands and feet

These symptoms, however, are not specific to kidney disease and could relate to several other diseases.

Thus, if you are older, have diabetes or high blood pressure, or a member of your family has chronic kidney disease, you should be examined by a doctor regularly who can perform some simple tests to detect the disease early:

  • A test for protein in the urine … too much protein in your urine suggests that your filtering units have been damaged.
  • Calculating your glomerular filtration rate (GFR), a measure of kidney function … you are tested for creatinine (a substance that helps your muscles produce energy and which builds up as a waste in your blood when your kidney function is reduced) … the results, combined with other factors, are used to calculate your GFR, ie how well your kidneys are functioning.
  • A blood urea nitrogen (BUN) blood test … BUN is another waste that builds-up in your bloodstream when your kidney function is reduced.
How to treat kidney disease

The secret is to have your blood glucose levels and blood pressure under control. Doing so can help to prevent kidney disease or keep it from getting worse.


The most important treatments for kidney disease are to keep tight control of your blood glucose levels and blood pressure.

The best way to keep your blood glucose levels under control is to follow the Beating Diabetes Diet ….. a plant-focused diet consisting of natural (non-processed) foods that are … low in sugar … low in fat … low in salt … high in fibre … have a low GI … contain only a little meat … washed down with lots of water … excluding eggs and all dairy products (milk, cheese etc).

The same diet will help you control your blood pressure.

Blood pressure can have a dramatic effect on the rate at which the disease progresses. Even a mild rise in blood pressure can quickly make kidney disease worsen. Four ways to lower your blood pressure are to:

  • lose weight
  • eat less salt
  • avoid alcohol and tobacco, and
  • get regular exercise

If you manage to get control over your diabetes and hypertension, you will slow the deterioration in your kidney functions and perhaps even stop it from getting worse. 

Drugs to lower blood pressure

If, after changing your diet and lifestyle, you are still having problems with your blood pressure, you can get a prescription from your doctor for medicines that will control your blood pressure.

Several kinds of blood pressure drugs are available. However, not all are equally good for people with diabetes. Some raise blood glucose levels or mask some of the symptoms of low blood glucose. Doctors usually prefer people with diabetes to take blood pressure drugs called ACE inhibitors.

Indeed, ACE inhibitors are recommended for most people with diabetes, high blood pressure and kidney disease. Recent studies suggest that ACE inhibitors, which include captopril and enalapril, slow kidney disease in addition to lowering blood pressure. And these drugs are helpful even for people who do not have high blood pressure.

Low protein diet

Protein increases how hard the kidneys work. Thus, another treatment some doctors use with patients who have large amounts of protein in their urine is a low-protein diet.

A low-protein diet can reduce the amount of protein that gets through the filtering process to the urine. But you should never start a low-protein diet without talking to your health care team.

Another trick is to concentrate on the protein you get from vegetables as the protein in animal products (meat, fish and dairy) is harder on the kidneys.

End-stage renal disease

End-stage renal disease (ESRD) is the complete and irreversible failure of your kidneys.

When your kidneys stop working completely, your body fills with extra water and waste products, a condition known as uraemia. You will feel tired and weak because your body needs clean blood to function properly. Your hands and feet may swell up.

Untreated uraemia may lead to seizures or coma and will ultimately result in death, in just a few months at the most. To avoid this, you will need to undergo dialysis or kidney transplantation.


Dialysis artificially removes waste products and extra fluid from your blood when your kidneys can no longer do this. The two major forms of dialysis are haemodialysis and peritoneal dialysis.

In haemodialysis, your blood is sent through a filter that removes waste products. The clean blood is returned to your body. Hemodialysis is usually performed at a dialysis centre three times per week for 3 to 4 hours each session.

In peritoneal dialysis, a fluid is put into your abdomen. This fluid captures the waste products from your blood. After a few hours, the fluid containing your body’s wastes is drained away. Then, a fresh bag of fluid is dripped into the abdomen.

Patients can perform peritoneal dialysis themselves. Patients using continuous ambulatory peritoneal dialysis (CAPD) change fluid four times a day.

Another form of peritoneal dialysis, called continuous cycling peritoneal dialysis (CCPD), can be performed at night with a machine that drains and refills the abdomen automatically.

Kidney transplant

A kidney transplant involves surgery in which your diseased kidneys are removed and a healthy kidney from a donor is put in its place.

The donated kidney may come from an anonymous donor who has recently died or from a living person, usually a relative. The kidney that you receive must be a good match for your body. The more the new kidney is “like” you then the less likely your immune system is to reject it.

Your immune system protects you from disease by attacking anything that is not recognized as a normal part of your body. Your immune system will reject a kidney that appears too “foreign.”

You will need to take special drugs for the rest of your life to help trick your immune system and keep it from rejecting the transplanted kidney.

Potential future treatments for kidney disease

Regenerative medicine holds the potential to fully heal damaged tissues and organs, offering solutions for people who have conditions that today are beyond repair.

The techniques of regenerative medicine include:

  • Boosting the body’s natural ability to heal itself
  • Using healthy cells, tissues or organs from a living or deceased donor to replace damaged ones
  • Delivering specific types of cells or cell products to diseased tissues or organs to restore tissue and organ function

For people with chronic kidney disease, new techniques that regenerate tissues and organs may be developed in the future to help slow the progression of the disease.

The takeaway
  • Your kidneys are vital organs that keep your blood clean and chemically balanced.
  • Diabetes and high blood pressure are the two leading causes of kidney failure.
  • Chronic kidney disease increases the risk of heart attacks and strokes.
  • Kidney disease builds up silently and is often not detected until it is well advanced
  • A doctor can test for kidney disease by testing for protein in your urine, calculating your GFR, a measure of kidney function, and by testing your blood for BUN
  • The progression of kidney disease can be slowed ― by keeping your blood glucose and blood pressure under control ― but it cannot always be reversed.
  • Dialysis and transplantation can extend the lives of people with end-stage renal disease, ie the total loss of kidney function.

If you are in the early stages of kidney disease, you may be able to save your remaining renal function for many years by:

  • controlling your blood glucose
  • controlling your blood pressure
  • following a low-protein diet
  • maintaining healthy levels of cholesterol in your blood
  • taking an ACE inhibitor
  • quitting smoking


Author: Paul Kennedy

Paul D Kennedy is a qualified accountant and an international business consultant who used his skills as a researcher to uncover the mysteries of type 2 diabetes and gain control over his health and wellbeing.

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