One-third of people with type 1 diabetes and 10-20 per cent of people with type 2 diabetes develop kidney disease after living with diabetes for 15 years or more. To understand how this complication develops, you need to know a little bit about the structure and function of the kidneys. The kidneys maintain the body's internal environment by controlling its fluid and electrolyte levels, and by removing its waste products. Each kidney contains approximately one million microscopic units called nephrons, which filter out waste products from the blood. Over long periods of time, high blood sugar levels damage the tiny blood vessels in the kidneys, making them thicker and clogged, and impairing the filtering ability of the nephrons. As a result, they are less able to filter wastes and impurities from the blood properly. Waste products in the bloodstream then build up to harmful levels. At the same time, some of the nutrients and proteins that should remain in the blood leak out of the blood vessels into the urine. The blood vessels in the kidneys can be further damaged by high blood pressure or kidney infections.
One of the substances that appear in the urine when the filters are damaged is protein and a particular protein called albumin appears in the urine at a very early stage of diabetic kidney damage. Albumin in the urine is also called albuminuria and a current test can detect the presence of very small amounts (microalbuminuria). The availability ofthese tests is one reason why you will be asked to provide a urine sample at each of your diabetic clinic visits, even if you are normally performing blood tests for glucose. Sometimes you may get a positive result from the albumin test, which may in fact be caused by a urinary infection. Your clinic will check your urine sample to exclude this.
Your doctor will want to keep a closer eye on you if albumin is detected in your urine because there is the possibility of more serious kidney damage and even kidney failure in the long term. This is even more important if, like many people with albuminuria, you also have raised blood pressure. The two tend to go together because the kidneys also have a role in controlling blood pressure. Recent research has shown that treating high blood pressure in people with diabetes can dramatically slow down the effect of diabetes on their kidneys.
At the moment, those people who do eventually suffer from kidney failure may need treatment either by dialysis (a kidney machine) or by a transplantation, but a lot of research is being done which may one day make this unnecessary.
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