Diabetes & Kidneys
Diabetes mellitus is a disease caused by the lack of insulin in the body or the body's inability to properly use normal amounts of insulin.
In diabetes, the body does not properly process and use certain foods, especially carbohydrates and fats. Glucose is a simple sugar that is the main source of energy for the body's cells. The human body normally converts carbohydrates to glucose. To enter cells. glucose needs the help of insulin, a hormone produced by the pancreas. When a person does not make enough insulin, or the body is unable to use the insulin that is present, the body cannot process the glucose, and it builds up in the bloodstream. The presence of high levels of glucose in the blood or urine is usually a clear sign of diabetes.
Over a period of time, unhealthy changes can occur in different body organs of a person with diabetes, including damage to the kidneys.
What are the kidneys?
Most people have two kidneys. They are located near the middle of your back, just under the ribcage. Each kidney weighs about 150g. and is about the size of an adult fist. They are bean-shaped and reddish brown in colour.
The kidneys perform crucial functions that affect all parts of the body.
What do the kidneys do?
The kidneys have four main roles in the body.
Are there different types of diabetes?
There are several types of diabetes. The most common are Type 1 and Type 2.
Type 1 - Juvenile Onset Diabetes: Type 1 diabetes, also known as insulin dependent diabetes (IDDM), tends to occur in young adults and children. In Type 1 diabetes, the body produces little or no insulin. People with IDDM must receive daily insulin injections.
Type 2 - Adult Onset Diabetes: Type 2 diabetes, also known as non-insulin dependent diabetes (NIDDM), usually develops in people over the age of forty. It may also develop in people who are overweight. Many are not aware that they have the disease. The pancreas produces close to normal amounts of insulin, but the body is unable to use it properly. Many people with Type 2 diabetes do not respond normally to their own or to injected insulin - this is called insulin resistance.
In India Type 2 diabetes is also seen in young people below the age of 45 years and is called MODY (Maturity Onset Diabetes in the Young). Some people with Type 2 diabetes control their blood sugar with diet and an exercise program leading to weight loss. Others must take pills that stimulate production of insulin; still others require injections of insulin.
How does diabetes affect the kidneys?
Diabetes can affect the kidneys in a number of ways but one of the most important complications is diabetic nephropathy. This is a kidney condition that occurs only in people with diabetes mellitus and results in progressive damage to the small filtering units of the kidney (glomeruli). This eventually leads to large amounts of protein in the urine, high blood pressure and declining kidney function. Even when drugs and diet are able to control diabetes, the disease can lead to nephropathy and kidney failure.
Diabetes is the second most common cause of kidney failure in India. About 20% of the people who need dialysis (artificial kidney treatment) or kidney transplantation in India have usually diabetic nephropathy.
What are the signs of diabetic kidney disease?
It is possible for individuals to have serious kidney damage without being aware of it. There may be no specific symptoms of diabetic kidney disease until the kidneys fail completely. Early signs or risk factors include:
Symptoms related to kidney failure usually occur only in late stages of the disease, when kidney function has diminished to less than 25 percent of normal capacity. For many years before that point, kidney disease of diabetes exists as a silent process.
Damage to the kidney is reflected in the amount of protein in the urine. Initially, the amount of protein is very small, but gradually, over a number of years, the amount of protein in the urine increases. The stage where routine tests do not detect protein in the urine, but still protein is present in very small quantities is called microalbuminuria. This can be detected by special tests and is reversible by certain class of drugs.
How does diabetes damage the kidneys?
Diabetes can cause damage to blood vessels and nerves and can prompt an increase in urinary infections.
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.
The delicate blood vessels in the filters of the kidney (the glomeruli) may be damaged. In the early stage, this damage is demonstrated by small amounts of protein in the urine (microalbuminuria).
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 (oedema). After a number of years, the kidney's filters can become so damaged by diabetes that the kidneys fail completely. Because smoking also damages the blood vessels, it worsens the complications of diabetes. People with diabetes should try to stop smoking completely or never start.
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. If urine builds up in the bladder, the pressure can cause it to flow back into the kidneys and cause scarring to kidney tissue.
Infections: Urine of people with diabetes has high sugar content. This encourages growth of bacteria and kidney infections may occur. People with diabetes must take special care to ensure any infections are treated immediately.
Who can get diabetic nephropathy?
Diabetic nephropathy is a long-term complication of diabetes but only 20-30% of people with diabetes will develop diabetic nephropathy. It is not entirely understood why only a small number of people with diabetes develop diabetic nephropathy.
However, a number of factors appear to increase the risk of kidney disease. These include:
It is important to realize that these are only risk factors and it is possible to have no risk factors and still develop kidney problems. Conversely, there are some people with all the risk factors who do not develop kidney problems.
What happens if the kidneys fail?
If a personís kidneys are about to fail, they might experience symptoms such as tiredness, nausea and vomiting. They may also find that they need less insulin than usual. When the kidneys fail, wastes and fluids will accumulate in the body and dialysis treatments or a kidney transplant is needed.
The survival of kidneys transplanted into diabetes patients is about the same as survival of transplants in people without diabetes. Dialysis for people with diabetes also works well. Even so, people with diabetes who receive transplants or dialysis may experience more medical problems and death because of other complications of the diabetes, such as damage to the heart, eyes and nerves.
Some people with diabetic kidney failure will be suitable for a combined kidney and pancreas transplant. If successful they will regain normal kidney function and will have normal blood sugar levels meaning they can stop using insulin.
Why is high blood pressure so important?
High blood pressure, or hypertension, is a major factor in the development of kidney problems in people with diabetes. Both a family history of and the presence of high blood pressure appear to increase chances of developing kidney disease. High blood pressure also accelerates the progress of kidney disease where it already exists.
High blood pressure in people with diabetes is usually defined as blood pressure exceeding 130/85 mm Hg. The first number is the systolic pressure and the second number is diastolic. The terms systolic and diastolic refer to pressure in the arteries during contraction of the heart (systolic) and between heartbeats (diastolic).
Hypertension can be seen not only as a cause of kidney disease, but also as a result of damage created by the disease. Early detection and treatment of even mild hypertension are essential for people with diabetes.
How can kidney disease be slowed & prevented?
Certain tests like detection of microalbuminuria can help to detect kidney damage at an early stage. There are also treatments, which may help to delay kidney failure. It is usually 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 if you have diabetes.
To help prevent kidney damage:
For more information please consult your family doctor or be in touch with your National Kidney Foundation (India).
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