Diabetes is a very common disease, which, if not treated, can be very dangerous. There are two types of diabetes. They were once called juvenile-onset diabetes and adult diabetes. However, today we know that all ages can get both types so they are simply called type 1 and type 2 diabetes.
Type 1, which occurs in approximately 10 percent of all cases, is an autoimmune disease in which the immune system, by mistake, attacks its own insulin-producing cells so that insufficient amounts of insulin are produced - or no insulin at all. Type 1 affects predominantly young people and usually makes its debut before the age of 30, and most frequently between the ages of 10 and 14.
Type 2, which makes up the remaining 90 percent of diabetes cases, commonly affects patients during the second half of their lives. The cells of the body no longer react to insulin as they should. This is called insulin resistance.
In the early 1920s, Frederick Banting, John Macleod, George Best and Bertram Collip isolated the hormone insulin and purified it so that it could be administered to humans. This was a major breakthrough in the treatment of diabetes type 1.
Insulin is a hormone. Hormones are chemical substances that regulate the cells of the body and are produced by special glands. The hormone insulin is a main regulator of the glucose (sugar) levels in the blood.
Insulin is produced in the pancreas. To be more specific, it's produced by the beta cells in the islets of Langerhans in the pancreas. When we eat, glucose levels rise, and insulin is released into the bloodstream. The insulin acts like a key, opening up cells so they can take in the sugar and use it as an energy source.
Sugar is one of the top energy sources for the body. The body gets it in many forms, but mainly as carbohydrates that are broken down to glucose during the digestive process. Examples of food rich in carbohydrates are pasta, rice, bread, potatoes, and of course, all sorts of sweets.
The cells of a person with diabetes have problems taking up glucose due to either the lack of insulin or a resistance to insulin. Instead, the sugar remains in the blood, resulting in the rise of blood glucose levels.
People with type 1 diabetes must have injections of insulin every day. Each diabetic patient needs an exact dose of insulin, calculated especially for him or her. An overdose of insulin lowers the blood sugar concentration. If it becomes too low, it can result in a coma and eventually death. An overdose is treated by giving the patient sugar in a form that is as pure as possible - for example, orange juice or table sugar. If the patient is in a coma, glucose must be injected directly into the bloodstream.
If a diabetic gets too little insulin, he or she can go into a coma just as when overdosing insulin. The two types of coma are very hard to distinguish from each other without testing the blood glucose levels of the patient. If the levels are low, the patient suffers from an overdose of insulin. If blood glucose levels are high, the patient doesn't have enough insulin.
So how is insulin for medical use made? For a long time insulin was extracted from the pancreases of cattle or pigs, and then it was purified so that it could be safely administered to humans. Today, it's more common to instruct genetically modified bacteria or yeast to produce a perfect copy of human insulin.
In type 1 diabetes the body's immune system erroneously attacks its own beta cells, thereby destroying insulin production. Why does this happen? Scientists do not know, but it is likely that the condition develops gradually in a series of steps. Starting from a hereditary predisposition, various environmental influences (viral infections and poisoning are suspected) have to take effect, one after the other, before the self-destruction of insulin begins.
With insulin treatment, a type 1 patient can live a perfectly normal life. Left untreated however, type 1 diabetes can rapidly lead to a life-threatening situation. The kidneys strive to remove the excess glucose, which pulls water with it and leads to heavy urination and an insatiable thirst. The fat cells are broken down to counter sugar loss, and toxic levels of acids build up in the blood - a condition known as ketoacidosis.
Symptoms of type 1 diabetes
Type 2 diabetes begins with insulin resistance. This means that the cells don't react to insulin the way they are supposed to. Normally, insulin binds to receptors on the cell surface. This activates the cell's glucose transporter molecules to form a doorway in the cell membrane so that glucose can enter the cell. However, when insulin resistance occurs, there's a reduced response to the insulin signals. Therefore, fewer doorways are formed and some glucose is locked out of the cells.
Type 2 diabetes is often hard to discover. An average of seven years passes from the onset of the disease to its diagnosis. This means that a fraction of the patients already suffer damage to their blood vessels, kidneys, eyes, or nerves. In most cases, type 2 diabetes patients are instructed to lead a life with "a healthy diet and lots of exercise." About one out of three patients receive insulin. Many patients are treated with a variety of oral drugs that affect blood glucose levels in various ways.
Symptoms of type 2 diabetes
Diabetes is a very common and rapidly growing disease. Type 2 diabetes was once a problem of industrialized nations, but it's fast becoming a global epidemic. In the year 2025, the number of adults with diabetes in the world is expected to be 300 million. That is approximately the same as the entire population of the United States in 2002.
It is estimated that 1/3 of Americans born in the year 2000 will develop diabetes.
First published February 2009
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