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Diabetes mellitus is a disorder in which blood levels of glucose are abnormally high because the body doesn’t release or use insulin adequately. Blood sugar levels vary throughout the day, rising after a meal and returning to normal within 2 hours. They are normally between 70 and 110 milligrams per decilitre of blood in the morning after an overnight fast.
Causes.People with type I diabetes mellitus (insulin-dependant diabetes) produce little or no insulin at all. Most people with this type of diabetes had developed the disease by age 30. Scientists believe that a viral infection or a nutritional factor in childhood or early adulthood cause the immune system to destroy the insulin-producing cells in the pancreas. Some genetic predisposition is most likely needed for this to happen. Whatever the cause, in type I diabetes more than 90% of the insulin-producing cells are permanently destroyed. The resulting insulin deficiency is severe, and to survive, a person must regularly inject insulin.
In type II diabetes mellitus (non-insulin-dependant diabetes), the pancreas continues to manufacture insulin, sometimes even at higher than normal levels. However, the body develops resistance to its effects, resulting in a relative insulin deficiency. Type II diabetes may occur in children and adolescents but usually begins after age 30 and becomes progressively more common with age. Obesity is a risk factor for type II diabetes. It also tends to run in families.
Other less common causes of diabetes are abnormally high levels of corticosteroids, pregnancy (gestational diabetes), drugs, and poisons that interfere with the production or effects of insulin, resulting in high blood sugar levels.
Symptoms. When the blood sugar level rises, glucose passes into the urine and the kidneys excrete additional water to dilute the large amounts of glucose lost. Because the kidneys produce excessive urine, a person with diabetes urinates large volumes frequently (polyuria). The excessive urination creates abnormal thirst (polydipsia). Because excessive calories are lost in the urine, the person loses weight. To compensate, the person often feels excessively hungry (polyphagia). Other symptoms include blurred vision, drowsiness, nausea, and decreased endurance during exercise. In addition, people whose diabetes is poorly controlled are more susceptible to infections.
The diagnosis of diabetes is made when a person has abnormally high blood sugar levels which are often checked during a routine physical examination. A doctor may also check blood sugar levels to find the possible cause of such symptoms as increased thirst, urination or hunger, or if the person has typical risk factors, such as a family history of diabetes, obesity, or frequent infections.
To measure the blood sugar level, a blood sample is usually taken after the person has fasten for about 8 hours, but it may be taken after eating. Some elevation of blood sugar levels after eating is normal, but even then the levels shouldn’t be very high. In people over 65 years old, the test is best performed after fasting because older people have a greater increase of blood sugar levels after eating.
Another kind of blood test, an oral glucose tolerance test, may be performed in certain situations. In this test, a person fasts, has a blood sample taken for the fasting blood sugar level, and then drinks a special solution containing a standard amount of glucose. More blood samples are then obtained over the next 2 to 3 hours.
The main goal of diabetes treatmentis to keep blood sugar levels within the normal range as much as possible. It also requires attention to weight control, exercise, and diet. However, weight reduction and increased exercise are difficult for most people with diabetes. Therefore, either insulin replacement therapy or an oral hypoglycaemic medication is often needed. Exercise directly lowers blood sugar levels, often reducing the amount of insulin needed. Diet management is also very important; people with diabetes shouldn’t eat too much sweet food and should eat their meals on a regular schedule.
Most people with diabetes benefit greatly from learning about their disease and what they can do to help control it. All diabetics must understand how diet and exercise affect their blood sugar levels and be aware of how to avoid complications, such as checking their skin for ulcerations. They must also take special care to avoid foot infections and can often benefit from having their toenails cut by a podiatrist. Yearly eye examinations are essential to check for changes in the blood vessels that can lead to blindness (diabetic retinopathy). In case of injury or high or low blood sugar levels, people with diabetes should always carry a card or wear a Medic Alert bracelet identifying the disease.