What is diabetic Nephropathy?
Diabetic nephropathy is the kidney disease that occurs as a result of diabetes. It is a leading cause of kidney failure in Europe and the USA. After many years of diabetes the delicate filtering system in the kidney becomes destroyed, initially becoming leaky to large blood proteins such as albumin which are then lost in urine. This is more likely to occur if the blood sugar is poorly controlled.
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1. It begins with a tiny amount of protein appearing in the urine - this is called microalbuminuria |
Do all diabetics develop nephropathy?
The overall risk of developing diabetic nephropathy varies between about 10% of type II diabetics (diabetes of late onset) to about 30% of type I diabetics (diabetes of early onset). There are many factors, some known and others not, that affect the individual risk of developing diabetic nephropathy. Some of the factors that are known to increase the likelihood of getting diabetic nephropathy include:
Indo-Asian or Afro-Carribean background |
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Male |
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Relatives have had kidney disease or high blood pressure |
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Diabetes began in teens |
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Blood sugar control is poor |
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High blood pressure |
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Smoking |
Will I need a kidney biopsy?
Given the relatively predictable nature of diabetic nephropathy , a kidney biopsy is usually not needed. You will be evaluated by history, examination, as well as blood and urine tests and a kidney ultrasound examination. If there are unusual features, then further investigations may be needed to define the kidney condition, and this may well involve a biopsy.
Does diabetic nephropathy have any other effects?
High blood pressure almost always develops or worsens in diabetic nephropathy, and can be the first abnormality to develop.
Diabetic nephropathy is also a sign of worsening blood vessel disease throughout the body. Diabetic eye disease is usually present by this stage indicating damage to smaller blood vessels. Larger blood vessels (arteries) are almost always affected leading to heart attacks, strokes, and circulatory disease occurring more often and at a younger age than usual.
Commonly diabetes will have also resulted in damage to small nerves causing "diabetic peripheral nephropathy" and "autonomic neuropathy".
What can be done to reduce the risk of problems?
Blood glucose control
Good blood glucose control can prevent the development and slow the progression of diabetic nephropathy, as well as preventing the other complications of diabetes, even if kidney failure has developed. This can not be achieved by tablets and/or insulin alone, but requires a good diet too. Achieving these things will involve discussion with doctors, nurses and dieticians.
Blood pressure control
The recommended target blood pressure is 125/75mmHg in diabetic patients. This usually requires more than one type of tablet to achieve. If you are overweight, losing weight will help too.
Using ACE inhibitors and AT II antagonists
Two classes of drug used to control blood pressure deserve special mention. These are the Angiotensin-Converting Enzyme (ACE) inhibitors and angiotensin II (AT II) receptor antagonists. Many studies have documented the greater potency of ACE inhibitors at reducing proteinuria and the progression of kidney disease compared to other classes of drug. These drugs not only reduce blood pressure in the large blood vessels, but also directly in the kidneys' filtering system (called glomeruli). Although these drugs tend to be preferentially used, they need to be monitored as they may have a detrimental effect on some people. It is thought that AT II receptor antagonists will have a similar effect, and these are often used in those unable to tolerate ACE inhibitors.
Diet
A modest reduction in dietary protein intake may be of benefit in those who already have kidney impairment. However this is a controversial and uncertain area, because the effect may be small if other things are well controlled, and low protein diets can be hazardous. Many (eg the American Diabetic Association) recommend moderate restriction of dietary protein. Other aspects of diet (including energy, calcium and phosphate intake) are important in renal failure, and the assistance of a renal dietitian is usually required.
Controlling blood lipids and cholesterol
Although the role of lipid-lowering is unclear in the course of diabetic nephropathy, it helps to prevent heart disease and possibly strokes. Lowering blood lipids requires both dietary and drug treatment, with the current available data pointing towards a target cholesterol of 5.2mmol/l.
Smoking
You really shouldn't smoke, not only for the sake of your kidneys, but also for the sake of your heart and brain blood vessels. Smokers die earlier than non-smokers, but diabetic smokers die much earlier and often develop serious circulation problems at a young age.
What is the treatment?
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Stage |
Assessment |
Treatment |
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No proteinuria |
Monitor blood pressure (BP) Monitor blood glucose Screen for microalbuminuria if type I diabetic for over 5yrs, or type II diabetic |
Aim under 130/85mmHg Aim HbA1c under 7% Dietary advice for sugar and fat STOP SMOKING |
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Microalbuminuria |
Close monitoring of blood pressure, blood glucose, and blood lipids. Monitor urinary protein and 24 hour creatinine clearance (measure of kidney function) |
Add further blood pressure lowering drugs if needed Aim total cholesterol under 5.2mmol/l Add ACE inhibitor if possible |
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Proteinuria |
Close monitoring of blood pressure, blood glucose, and blood lipids. Monitor urinary protein and 24hr creatinine clearance |
Aim BP <125/75mmHg Low protein diet |
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Declining kidney function |
Prepare for dialysis and/or transplantation |
Key Points
Diabetic nephropathy does not occur in all diabetics. |
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The risk of diabetic nephropathy is greater when the control of blood glucose is poor, as well as in those diabetic patients who have high blood pressure and are smokers. |
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Diabetic nephropathy is a sign of worsening blood vessel disease throughout the body, and is associated with an increased risk of heart attack, stroke and circulatory problems. |
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The risk and effect of diabetic nephropathy can be reduced by controlling blood sugar, blood pressure and cholesterol levels this can be achieved with a combination of good dietary control as well as medication |
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Smoking shortens life. It is vital to stop! |
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Please be aware that while we have made all effort to ensure that this information is accurate, we cannot guarantee that there are no mistakes. Also that the best management for individual patients may differ from that outlined here. Only the doctors caring for the patient will be able to advise on this.
