Diabetes and kidney damage

Uncontrolled or poorly controlled diabetes affects the kidneys and leads to a condition called diabetic nephropathy, which is a leading cause of chronic renal failure in many countries, and Malaysia is no exception.

DIABETES is a condition where blood sugar is raised (hyperglycaemia) due to defects of insulin secretion (type 1), insulin action (type 2), or a combination of the two. Diabetics suffer from abnormalities of carbohydrate, fat and protein metabolism.

According to the National Health and Morbidity Survey (NHMS) III in 2006, the overall prevalence of diabetes (known and newly diagnosed) was 11.6%. The prevalence increases with increasing age, viz: the prevalence was 2% in those aged 18 to 19 years and between 20.8% and 26.2% in those aged 50 to 64 years.

There was an increase in the national prevalence of known and newly diagnosed diabetics from 8.3% in NHMS II in 1996 to 14.9% in NHMS III in 2006 in those aged 30 years and above. The prevalence of newly diagnosed diabetics increased from 2.5% in 1996 (NHMS II) to 5.5% in 2006 (NHMS III).

Uncontrolled or poorly controlled diabetes affect the kidneys and leads to the condition called diabetic nephro-pathy, which is a leading cause of chronic renal failure in many countries, and Malaysia is no exception. This condition also leads to significant long-term morbidity and mortality.

The condition is characterised by protein in the urine (albuminuria) on two or more occasions three to six months apart, decline in the kidneys’ glomerular filtration rate (GFR), and raised blood pressure.

The exact cause of diabetic nephropathy is unknown. It is believed that uncontrolled high blood sugar leads to kidney damage, especially when there is also high blood pressure (hypertension). As not all diabetics develop this condition, it is believed that the individual’s genetic or family history may play a role as well.

When the blood sugar is too high, it damages the filtering units of the kidneys (nephron) and the blood vessels within (glomerulus). These structures thicken and form scar tissue. In the course of time, more and more of these structures are damaged and destroyed, resulting in the leakage of protein into the urine (albuminuria).

The peak incidence of diabetic nephropathy in diabetics is in their second decade of the condition. It is uncommon for it to develop in patients who have had diabetes for less than 10 years.

The likelihood of diabetic nephropathy is increased in those with risk factors, i.e. poor control of blood sugar, poor control of blood pressure, family history of kidney disease or hypertension, type I diabetes before the age of 30 years, and smokers.

Management

The goals of management are to prevent the nephropathy from worsening and to prevent the complications of diabetes from developing.

Keeping the blood pressure below 130/80mm Hg is an effective way of slowing damage to the kidneys. The angiotensin-converting enzyme (ACE) inhibitors and angio-tensin receptor blockers (ARBs) are the preferred medicines for treating hypertension in diabetics and those with signs of kidney disease. Careful blood pressure control is crucial in preventing the progression of diabetic nephropathy and other complications.

Ensuring that the blood sugar levels are at near normal levels will slow down the kidney damage, especially in the early stages of the nephropathy. This may require a combination of diet and medicines. The doses of the latter may need adjustment periodically.

Prevention

Appropriate patient information, patient compliance to management prescriptions and regular follow-up clinic or hospital visits are essential to the prevention and early recognition and management of diabetic nephropathy.

The management objectives are:

  • Optimal blood glucose control;
  • Control of hypertension; and
  • Avoidance of medicines that can damage the kidneys, e.g. commonly used non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, naproxen and antibiotics like the aminoglycosides.

There is ample evidence that the early and optimal management of diabetes will delay or prevent the onset of diabetic nephropathy.

It is prudent to remember that microalbuminuria is an independent predictor of cardiovascular morbidity in diabetics. Deaths from any cause in diabetics are also increased if there is microalbuminuria and macroalbuminuria. Even in the non-diabetic population, microalbuminuria is a predictor of coronary and peripheral vascular disease and death from cardiovascular disease.

It would be in the interest of all diabetics to always remember the axiom “prevention is better than cure”.

by Dr Milton Lum, a member of the board of Medical Defence Malaysia.

Read more @ http://thestar.com.my/health/story.asp?file=/2010/9/29/health/7068140&sec=health

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