Complications of Diabetes

Diabetic Nephropathy

What is diabetic nephropathy?

The kidneys work as a very delicate system of filtering the blood, which tend to allow certain waste elements to be passed in the urine while retaining important constituents such as cells and proteins. Diabetic nephropathy is a complication of diabetes which tends to develop after many years and results in progressive loss of ability of the kidneys to function.  Like a sieve which becomes ‘leaky’, the kidney intially becomes leaky to proteins such as albumin which are lost in the urine.

Diabetic nephropathy usually progresses slowly through several stages.

  1. Leakage of tiny amounts of protein – called microalbuminuria
  2. Increasing proteinuria leading to loss of large amounts of protein, causing ‘nephrotic syndrome’ a condition defined by fluid retention and swelling due to low amounts of protein
  3. The kidneys become less able to remove ‘poisons’ from the blood resulting in a build up in the levels of various chemicals such as urea and creatinine. This is known as ‘chronic renal failure’ or ‘end stage kidney disease’

Does everyone with diabetes get diabetic nephropathy?

Diabetic nephropathy occurs in up to a third of all people with diabetes. The individual risk of developing kidney problems depends on whether you have type 1 or type 2 diabetes. Not everyone with ‘long standing diabetes ‘ gets nephropathy. The reason for this is not known.  It is known that the following factors increase your risk.

  • High blood pressure
  • Smoking
  • Poor control of blood sugar
  • Being male

Can it be prevented?

Unfortunately it is not possible to be absolutely sure of prevenitng this complication of diabetes, but as with most other complications there is a lot you can do to reduce your risk. Research has shown that these measures are useful even after the early stages of nephropathy have developed. Early detection is therefore important and all diabetes clinics now routinely screen for minute amounts of protein in the urine or microalbuminuria.

The following have been shown to be of benefit

  • Keeping your blood sugars within a safe range
  • Keeping your blood pressure within a safe range
  • Controlling blood lipids and cholesterol
  • Using ACE inhibitors and AT II antagonists (see section on Angiotensin Converting Enzyme inhibitors) . These drugs are useful in preventing progression of nephropathy and act by reducing blood pressure in the large blood vessels as well as reducing pressure within the kidney’s filtering system
  • Modifying your diet – this is controversial, but is thought to be of some benefit once kidney problems have started
  • Stopping smoking

What are the symptoms?

During the early stages of diabetic nephropathy people are usually without any symptoms. Small amounts of protein leak into the urine (microalbuminuria). Normally, protein is not found in urine, except during periods of high fever, strenuous exercise, pregnancy, or infection.

As the condition progresses, you may have:

  • Swelling of the feet and legs and later throughout the body.
  • rise in blood pressure.
  • Larger amounts of protein leaking into the urine (macroalbuminuria, also known as overt nephropathy).
  • Rising levels of fats (cholesterol and triglycerides) in the blood.

Once the kidneys are more severely damaged, blood sugar levels may drop because the kidneys retain insulin in the body. Other symptoms may occur as nephropathy worsens. See the section on Chronic Renal Failure for more information. Not uncommonly diabetes also results in damage to small nerves causing peripheral nephropathy.

How is nephropathy diagnosed?

Detecting protein in the urine is the cornerstone of diagnosis.

  • Urine dipstick test detects moderate amounts of protein
  • A microalbumin test is used to look for small amounts of protein
  • Your doctor is likely to request a 24 hour urine collection in order to determine how much protein you pass
  • If the diagnosis is in doubt a kidney biopsy may be requested

Is diabetic nephropathy treatable?

Prevention is the best way to avoid lasting kidney damage from diabetic nephropathy. Once the condition is established, most people tend to progress slowly to chronic renal failure. The factors mentioned above in ‘prevention’ are all of importance in preventing worsening of kidney function. People who have diabetic nephropathy are at greater risk of developing cardiovascular disease, so it is important that they try to lower the risk of heart problems. This includes keeping cholesterol at a normal level, regular exercise, a low-fat diet, and not smoking. Lowering cholesterol may also help to reduce the level of protein in the urine.

When end stage kidney failure is reached dialysis and transplantation are options. Early detection and treatment can slow the rate of ‘kidney loss’ and significantly lengthen the time it takes to progress to dialysis or transplantation.

What are the effects of kidney failure?

The symptoms of kidney failure are very insidious in onset and are not very specific as they may be encountered in a variety of other conditions.

  • Feeling tired  - marked lack of energy
  • Feeling ill.
  • Passing more urine – more noticeable at night
  • Nausea
  • Altered taste sensation
  • Itching
  • Swelling of the legs
  • Shortness of breath

What is Dialysis?

When the kidneys fail to a level that only 10-15% of their function remains, they are no longer able to excrete the required amounts of fluid and toxic substances. Fluid retention follows and toxic chemicals build up with resulting impact on quality of life. Dialysis can help at this stage by taking on some of the filtering function of your kidneys. There are two main methods of dialysis.

  • Haemodialysis – where your blood is passed through a special filtering machine which clears the toxic substances before being returned to your body
  • Peritoneal dialysis – where the dialysis fluid is placed in your tummy. The lining of your abdominal cavity serves as a filter membrane. The fluid is subsequently removed removing the filtered toxins.

Is a kidney transplant an option?

Yes. See separate leaflet on having a kidney transplant.


Dr Nishan Wijenaike, Consultant Physician
West Suffolk Hospital Diabetes Service
October 2002