Diabetes and Kidney Disease

Diabetes is a disease that is caused by the lack of insulin in the body or the body's inability to properly use normal amounts of insulin.

The body converts the food we eat into sugar (glucose). The body needs this sugar, in the form of energy, to perform its functions. The hormone insulin, produced by the pancreas, regulates the amount of glucose (sugar) in the blood. If the body lacks insulin or does not use the insulin properly, then this imbalance results in high blood sugar. Eventually many unhealthy changes can occur in different body organs, including the kidneys.

How diabetes affects the kidneys

  • Damage to blood vessels
    Even with the use of injected insulin, people who have had diabetes for some time often suffer from damage to the small blood vessels of the body. This may cause damage to the retina of the eye and result in loss of vision. Also, the delicate blood vessels in the filters of the kidney may be damaged. At the early stage, this damage is shown by finding protein in the urine.

Sometimes at a later stage, so much protein is lost from the blood that water from the blood moves into the body tissues and causes swelling (edema). After a number of years, the kidneys' filters can become so damaged by diabetes that the kidneys fail.

  • Damage to nerves
    Diabetes can also damage the nerves in many parts of the body. When the bladder is affected, it may be difficult to pass urine. The pressure from urine building up in the bladder can damage the kidneys.
  • Infections
    The urine of people with diabetes has a high sugar content. This encourages the growth of bacteria and kidney infections may occur. People with diabetes must take special care to avoid infections and have them treated immediately.

Types of diabetes

There are several types of diabetes. The most common ones are Type 1 and Type 2.

Type 1 - Juvenile Onset Diabetes

  • Develops mainly in young people
  • Is caused by an inability of the pancreas to produce enough insulin
  • Requires regular insulin injections

Type 2 - Adult Onset Diabetes

  • Usually develops in people after their teenage years
  • The pancreas can produce insulin, but the body has difficulty using it properly
  • Treatments include diet, exercise and medication (pills, insulin injections or both)

Signs of developing kidney disease

Signs of early kidney damage can develop in as many as 50% or more of people with diabetes. If left untreated, this could lead to more kidney damage or kidney failure.

You could have serious kidney damage without being aware of it. There are usually no specific symptoms of kidney disease until the damage is severe. However, if you have diabetes, you should be tested once a year to see if diabetes has affected your kidneys. Your doctor can arrange a urine test for protein (a random urine test for “albumin to creatinine ratio”), and a blood test to check how well your kidneys are functioning (the “serum creatinine”).

What happens when kidneys fail

When your kidneys are about to fail you might experience tiredness, nausea and vomiting. You could also retain salt and water, which could cause swelling of your feet and hands, and shortness of breath. You may also find that you need less insulin than usual.

When the kidneys fail, wastes and fluids will accumulate in your body and you will need dialysis treatments or a kidney transplant. You may be referred to a nephrologist (a kidney specialist) if your doctor thinks the damage to your kidneys is severe.

How to prevent kidney damage

There are special treatments (including proper food choices and medications) which may help to delay kidney failure. It is necessary to start these treatments as soon as your doctor notices any of the early signs or risk factors. Therefore, you should stay in close touch with your doctor.

There are many things you can do to help prevent kidney damage:

  • Have your urine, blood and blood pressure checked regularly by your doctor
  • Maintain good control of your blood sugar
  • Control high blood pressure (less than 130/80* on most readings)
  • Stop smoking
  • Exercise regularly
  • Make the proper food choices
  • Avoid excess alcohol
  • See your doctor if you think you have a bladder infection
  • Get enough sleep
  • Ask your doctor about any new developments in the treatment of diabetes

* Blood pressure goals vary depending on the individual. Discuss your blood pressure goal with your doctor.


With acknowledgement to Dr. Philip A. McFarlane, FRCPC, nephrologist, at St. Michael’s Hospital in Toronto, Ontario, for his assistance in reviewing this information.

© 2004






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