Diabetes

Diabetes is the name of two diseases that have the same symptoms, excessive thirst and the production of large quantities of urine. Diabetes usually refers to dia­betes mellitus, by far the more common disease, in which the body cannot use sugar normally. In the other disease, diabetes insipidus, the pituitary gland or the hy­pothalamus, a part of the brain, functions abnormally.

Diabetes mellitus is a common disease, affecting an estimated 30 million people worldwide. About half of them do not know they are diabetic. The body of a dia­betic person is slow in using glucose (sugar), and so glucose builds up in the blood. The kidneys discharge some of the excess glucose into the urine. In severe cases of diabetes, fats and proteins also cannot be used normally.

Most doctors once believed that all cases of diabetes were caused by a lack of the hormone insulin. Insulin, which is produced by the pancreas, enables the body to use and store glucose quickly. Some diabetics do lack insulin. This form of the disease is called Type I diabetes (also known as insulin-dependent diabetes, IDDM). However, many diabetics—especially those who be­come diabetic after the age of 40—have normal or in some cases even above-normal production of insulin. Their bodies do not respond efficiently to the insulin. Doctors call this form of the disease Type II diabetes (also known as non-insulin-dependent diabetes, (NIDDM). In Europe and North America, about 80 percent of all diabetics have Type II, which is a milder form of the disease. In other parts of the world, more than 95 per cent of all diabetics have

Type II.

Symptoms of diabetes include excessive urination, great thirst, hunger, and loss of weight and strength. These symptoms may appear gradually—and even be unnoticed—in Type II diabetes. This kind of diabetes is most common in overweight individuals over the age of about 40.

In Type I diabetes, the more serious form of the dis­ease, the symptoms may occur suddenly. Type I diabe­tes usually strikes young people but can also occur in adults of any age. It hits some people so suddenly that the lack of insulin causes an emergency condition called diabetic ketoacidosis. The symptoms of this condition are excessive urination and thirst, loss of appetite, nau­sea, vomiting, and rapid deep breathing. It is vital that someone with these symptoms receives immediate treatment. If the victim does not receive attention imme­diately, he or she may go into a state of diabetic coma, which can lead to death.

Cause of diabetes is unknown. The disease is com­mon in some families, but many diabetics have no known family history of diabetes. Many researchers sus­pect that certain people inherit a tendency for develop­ing Type II diabetes. Additional factors, such as obesity or severe stress, may trigger the onset of the disease in such people. Some doctors believe that Type I diabetes also involves hereditary traits. These traits possibly cause the body's disease-fighting immune system to re­spond to certain viral infections by mistakenly attacking the insulin-producing cells of the pancreas.

Treatment. Diabetes cannot be cured, but proper treatment can improve a patient's condition consider­ably. Many diabetics live almost as long as people of normal health.

Type I diabetics need to receive daily doses of insulin. Some patients need more than one dose of insulin each day. To be effective, insulin must be absorbed into the bloodstream. It cannot be administered orally, because it is destroyed in the digestive system. Most diabetics who use insulin receive it by hypodermic injections. A small number of diabetics use portable pumps to inject insulin.

The dosage of insulin prescribed by the doctor de­pends on the patient's diet and exercising habits. If a dia­betic stops taking needed insulin, the amount of glu­cose in the blood may become excessive. This excess can result in diabetic ketoacidosis, and the patient may go into a diabetic coma.

Most Type 1 diabetics follow carefully planned diets consisting of planned amounts of carbohydrates, fats, and proteins. Most also test their urine or blood daily for glucose and for acetone, a substance produced when the effect of insulin is inadequate. A diabetic fol­lows the planned diet strictly—except if he or she has an insulin reaction, or insulin shock. This condition occurs when the effect of insulin is so great that the level of sugar in the blood becomes too low. The patient may perspire greatly and become nervous, weak, or even un­conscious. The condition can be treated quickly by hav­ing the patient eat food that is rich in sugar. Many dia­betics carry chocolate or sugar with them in case of an insulin reaction.

Many cases of Type II diabetes can be controlled by a diet that is low in calories. Some Type II diabetics whose condition cannot be controlled by diet alone have to use insulin or take oral drugs that reduce the level of glu­cose in the blood.

Complications. Diabetes can lead to serious compli­cations. For example, it may cause changes in the blood vessels of the retina. This condition is called diabetic ret­inopathy. When this condition is in its advanced stages, it is a major cause of blindness (see Blindness [Diseases]). Diabetes is known to cause similar changes in the blood vessels of the kidneys. This condition, called diabetic nephropathy, may lead to kidney failure. The nerves may also be affected by diabetes. This com­plication, known as diabetic neuropathy, can result in loss of feeling or abnormal sensations in different parts of the body. Various treatments can control many cases of diabetic retinopathy, diabetic nephropathy, and dia­betic neuropathy.

Diabetes can also lead to atherosclerosis, a form of arteriosclerosis (hardening of the arteries) that may cause a stroke, heart failure, or gangrene (see Arterio­sclerosis).

Research. Scientists are continually searching for ways to control, prevent, and cure diabetes. Since the 1960's, doctors have been experimenting with pancreas transplants and with transplants of the islets of Langerhans, the part of the pancreas that produces insulin. Since the 1970's, bioengineers have been working to de­velop and miniaturize an artificial pancreas. Such a de­vice could continuously measure the amount of glucose in the blood and release either insulin or glucose into the body to maintain a normal level of blood glucose. Other researchers working with the techniques of ge­netic engineering are trying to identify the hereditary traits that might contribute to diabetes and viruses or other agents that might be responsible for triggering Type I diabetes.

Diabetes insipidus is a rare disease in which the kid­neys cannot retain water that passes to them from the blood. The patient urinates excessively and becomes ex­tremely thirsty. The disease is caused by a lack of vaso­pressin, a hormone that controls the amount of water leaving the body as urine. Vasopressin is made by the hypothalamus and is stored in and released by the pitu­itary gland. A disease or injury that affects the hypothala­mus or the pituitary gland can cause this condition.

Most cases of diabetes insipidus cannot be cured, but the disease can be kept under control by taking vaso­pressin. See also Insulin; Hodgkin, Dorothy G; Hypoglycaemia.