Type 1 diabetes
Type 1 diabetes mellitus is an autoimmune disease in which the body attacks the insulin-producing cells in the pancreas and destroys them.
Autoimmune disorders are disorders in which the body’s immune system, which normally protects the body against foreign invaders, mistakenly identifies part of the body as foreign and attacks healthy tissue.
In the case of type 1 diabetes the body destroys the insulin-producing beta cells found in the islets of Langerhans within the pancreas. This means that the pancreas can’t produce insulin — a hormone that your body needs to regulate levels of sugar in the blood and within cells.
Type 1 diabetes usually starts during childhood. It used to be sometimes called juvenile diabetes or insulin-dependent diabetes, but because adults can also develop type 1 diabetes and because many people with type 2 diabetes also need insulin, these names have been dropped.
Doctors don’t know exactly why the body attacks itself like this, but certain virus infections may play a part as well as inherited (genetic) factors.
What are the consequences of having type 1 diabetes?
Many types of cells in the body need glucose as a fuel, and insulin is needed to move glucose from the bloodstream into the cells. In type 1 diabetes, with no insulin, or very little insulin, being produced by the pancreas, glucose in the bloodstream cannot move into the cells where it is needed. This leads to glucose accumulating in the bloodstream — this is called hyperglycaemia.
For the body to function well, blood glucose levels need to be kept within a healthy range, and high blood glucose (hyperglycaemia) can be the cause of many complications in people with diabetes. To combat hyperglycaemia, people with type 1 diabetes need to inject themselves with insulin several times a day to keep their blood glucose levels within a healthy range.
What are the symptoms of hyperglycaemia?
If you have a high blood glucose level, and little or no insulin, your body’s fat and muscle cells can’t take up glucose to use it for energy or to store it for later. Your body then tries to get rid of the excess glucose in your bloodstream by other methods. One of these is increased urination.
The high level of sugar in the bloodstream also draws out water from your body tissues. You will become dehydrated and feel thirsty due to the large amounts of fluid you are losing. Drinking more to relieve your thirst will lead to even more urination. Increased thirst and urination are often the first symptoms of type 1 diabetes to be noticed.
Another symptom of hyperglycaemia is tiredness — because the glucose in your bloodstream can’t get into your muscles and body cells where it’s needed as fuel (because of the lack of insulin). Blurred vision and weight loss are also symptoms of high blood glucose.
What are the complications of hyperglycaemia?
Having high blood sugar levels can lead to many complications both long term and short term.
Ketoacidosis
In the short term, if blood glucose levels remain high and hyperglycaemia goes untreated, a medical emergency called diabetic ketoacidosis may develop. This is when your body has no insulin to allow glucose to move out of the bloodstream and into the muscles and body cells. With the body’s cells unable to access glucose as an energy source, the body starts to break down fat cells to use as energy. Unfortunately, a by-product of the breakdown of fats is toxic waste products called ketones. The ketones can build up in the blood and lead to a coma and even death.
Heart and blood vessel disease
An increased risk of heart disease (including heart attack), stroke and peripheral vascular disease is a long-term complication of high blood glucose and diabetes. This is caused by deposits in small blood vessels which make the vessels thicken and leak.
Neuropathy
Long-term complications of high blood glucose include neuropathy (nerve damage). The excess glucose in the blood damages the tiny blood vessels supplying nerves. Eventually the nerves fail to transmit signals to the brain properly, or at all. This can lead to tingling, numbness or burning pains in the hands, feet and legs, as well as erectile problems in men.
Nephropathy
Kidney damage (nephropathy) is another long-term complication of high blood glucose levels. Tiny blood vessels in the kidney normally filter waste products and excess fluid from the bloodstream. These are then excreted by the kidney into the urine. However, in type 1 diabetes the kidney’s filtering system is damaged and waste products remain in the blood and protein leaks into the urine. Severe damage will lead to kidney failure, requiring dialysis or kidney transplantation.
Retinopathy
Damage to the blood vessels in the eye (retinopathy) is another complication of type 1 diabetes. This can lead to blindness. Cataracts and glaucoma are also more likely in people with type 1 diabetes than in people without.
Infections
An increased risk of infections — due to the immune system not functioning well — is yet another side-effect of high blood glucose.
Treatment and lifestyle issues
Because of the risk of developing complications from having high blood glucose levels, tight control of blood glucose so that it doesn’t rise or fall outside of a healthy range is very important in type 1 diabetes. This is usually achieved by a combination of insulin injections and self-monitoring of blood glucose.
The level of glucose in the bloodstream is influenced all the time by food eaten, level of exercise or activity, other stresses on the body, such as infection or major surgery, as well as by insulin dose. People with diabetes must continually adjust their insulin doses based on factors such as their blood glucose levels, when they are going to eat and how much exercise is planned, so that they can try to achieve good blood glucose control.
Risk factors for developing diabetes
It’s not clear which factors trigger the autoimmune process whereby the body attacks the insulin-producing cells of the pancreas and so causes type 1 diabetes. Inherited (genetic) factors plus exposure to certain viruses are thought to play a part.
Scientists are working hard to unravel the mystery of why some people get type 1 diabetes. They think that the inherited component is not enough on its own, because identical twins (who have exactly the same genes) do not always both get diabetes. So, clearly some other factors, like having certain viruses, come into play. Hopefully, these factors will be revealed in the not too distant future.
Last Reviewed: 14 September 2009
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