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  • Diabetes

    Quick Reference

    Reviewed by Pedro R. Guevara, MD

    Diabetes Mellitus is characterized by high blood sugar levels (hyperglycemia) and other metabolic derangements. These problems are caused by inadequate action of insulin (a hormone produced by the pancreas) on body tissues, due either to reduced circulating levels or resistance of target tissues to its actions. Because of the complications of this disorder, diabetes may be considered a syndrome consisting of metabolic abnormalities, microvascular disease (for example, vessels of the retina called retinopathy as well as vessels and small structures of the kidney called nephropathy), and peripheral and autonomic neuropathy.

    Approximately 16 million Americans are diabetic. Almost half of these people are unaware that they are diabetic and their condition goes untreated. The incidence of diabetes is growing with every year.

    Detailed Description

    Glucose is the end product of the carbohydrates that we consume on a daily basis and these carbohydrates are classified into:

    a) Complex sugars: vegetables, grains and starch.
    b) Simple sugars: refined sugars, fruits.
    c) Other sugars (for example, the lactose that is found in dairy products).

    After digestion, the glucose passes into our bloodstream, where it is available for use by the body cells for growth and energy.

    Insulin is required for the efficient transport of energy producing glucose into the body’s tissues. Insulin is a hormone produced by the pancreas, a large gland behind the stomach. In the absence of insulin, glucose cannot be effectively transported into cells and it accumulates in the blood

    Over time, high levels of glucose in the blood will cause damage to small vessels and nerves that supply vital organs such the heart, kidney, eyes, and extremities. If untreated, high blood glucose can lead to vascular disease that, among other things, causes blindness, atherosclerosis, heart attack, kidney disease, and gangrene. Proper treatment aimed at controlling blood glucose levels can help prevent these complications.

    When we eat, the pancreas automatically produces the right amount of insulin to transport the glucose from our blood into our cells. In people with diabetes, however, the pancreas either produces little or no insulin, or the body cells do not respond to the insulin that is produced. As a result, glucose builds up in the blood and spills over into the urine, leading to one of the most well–known signs of diabetes and insulin deficiency: the presence of sugar in urine (glycosuria). The body loses its main source of fuel even though the blood contains large amounts of glucose.

    The three main types of diabetes are:

    • Type I diabetes or Insulin-dependent diabetes mellitus (IDDM)
    • Type II diabetes or Noninsulin-dependent diabetes mellitus (NIDDM)
    • Gestational diabetes

    Type I Diabetes

    Insulin-dependent diabetes is considered an autoimmune disease. An autoimmune disease results when the body's own system for fighting infection (the immune system) turns against itself (a part of the body). In diabetes, the immune system attacks the insulin-producing beta cells in the pancreas and destroys them. The pancreas then produces little or no insulin.

    Someone with Type I diabetes needs daily injections of insulin to live. At present, scientists do not know exactly what causes the body's immune system to attack the beta cells, but they believe that both genetic factors and viruses are involved. Type I diabetes accounts for about 5 to 10% of diagnosed diabetes in the United States. It develops most often in children and young adults, but the disorder can appear at any age. Symptoms of Type I diabetes usually develop over a short period, although beta cell destruction can begin months, even years, earlier. Symptoms include increased thirst and urination, constant hunger, weight loss, blurred vision, and extreme tiredness. If not diagnosed and treated with insulin, a person can lapse into a life-threatening coma.

    Type II diabetes

    The most common form of diabetes is Type II diabetes. About 90 to 95% of people with diabetes have this kind. This form of diabetes usually develops in adults over the age of 40 and is most common among adults over age 55. About 80 percent of people with NIDDM are obese. In Type II diabetes, the pancreas usually produces insulin, but for some reason, the body cannot use the insulin effectively. The end result is the same as for Type I—an unhealthy buildup of glucose in the blood and an inability of the body to make efficient use of its main source of fuel. The symptoms of Type II diabetes develop gradually and are not as noticeable as in Type I. Symptoms include feeling tired or ill, frequent urination (especially at night), unusual thirst, weight loss, blurred vision, frequent infections, and slow healing of sores.

    Gestational Diabetes

    Gestational diabetes develops or is discovered during pregnancy. This type usually disappears when the pregnancy is over, but women who have had gestational diabetes have a greater risk of developing Type II diabetes later in their lives.

    Diabetes is widely recognized as one of the leading causes of death and disability in the United States. According to death certificate data, diabetes contributed to the deaths of more than 169,000 persons in 1992.

    Diabetes is associated with long-term complications that affect almost every major part of the body. It contributes to blindness, heart disease, stroke, kidney failure, amputations, and nerve damage. Uncontrolled diabetes can complicate pregnancy, and birth defects are more common in babies born to women with diabetes.

    Diabetes is not contagious. People cannot "catch" it from each other. However, certain factors can increase one's risk of developing diabetes. People who have family members with diabetes (especially Type II diabetes), who are obese, or who are African American, Hispanic, or Native American are all at greater risk of developing Type II diabetes.

    Type I diabetes occurs equally among males and females, but is more common in whites than in nonwhites. Data from the World Health Organization's Multinational Project for Childhood Diabetes indicate that Type I is rare in most Asian, African, and Native American populations. On the other hand, some northern European countries, including Finland and Sweden, have high rates of Type I diabetes. The reasons for these differences are not known.

    Type II diabetes is more common in older people, especially older women who are obese, and occurs more often among African Americans, Hispanics, and Native Americans. Compared with non-Hispanic whites, diabetes rates are about 60% higher in African Americans and 110 to 120% higher in Mexican Americans and Puerto Ricans. Native Americans have the highest rates of diabetes in the world. Among Pima Indians living in the United States, for example, half of all adults have Type II diabetes. The prevalence of diabetes is likely to increase because older people, Hispanics, and other minority groups make up the fastest growing segments of the U.S. population.

    Eye problems, such as glaucoma and cataracts, are common complications of diabetes. Eye issues generally appear any time after five years of Type I diabetes and at any time in Type II diabetics. Eye problems do not have to occur, however; if a diabetic maintains a good blood glucose level and blood pressure level, eye problems may be prevented.


    Before the discovery of insulin in 1921, most people with Type I died within a few years after the appearance of the disease. Although insulin is not considered a cure for diabetes, its discovery was the first major breakthrough in diabetes treatment.

    Today, daily injections of insulin are the basic therapy for Type I diabetes. Insulin injections must be balanced with meals and daily activities, and glucose levels must be closely monitored through frequent blood sugar testing.

    Diet, exercise, and blood testing for glucose are also the basis for management of Type II diabetes. In addition, some people with Type II diabetes take oral drugs or insulin to lower their blood glucose levels.

    People with diabetes must take responsibility for their day-to-day care. Much of the daily care involves trying to keep blood sugar levels from going too low or too high. When blood sugar levels drop too low—a condition known as hypoglycemia—a person can become nervous, shaky, and confused. Judgment may be impaired. Eventually, the person could lose consciousness. The treatment for low blood sugar is to eat or drink something with sugar in it.

    On the other hand, a person can become very ill if blood sugar levels rise too high, a condition known as hyperglycemia. Hypoglycemia and hyperglycemia, which can occur in people with Type I or Type II diabetes, are both potentially life-threatening emergencies. Doctors should monitor patients with diabetes and check them for complications. Doctors who specialize in diabetes are called endocrinologists or diabetologists.

    The goal of diabetes management is to keep blood glucose levels as close to the normal (non-diabetic) range as safely possible. A recent Government study, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), proved that keeping blood sugar levels as close to normal as safely possible reduces the risk of developing major complications of diabetes.

    Last updated: 11-May-04

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