Reviewed by Joseph Maloney, MD
Diabetes is a disease that affects an estimated 18 million people in the United States. It is a disorder marked by too much glucose (a form of sugar) in the blood. Glucose is carried by blood to cells and enters them with the help of the pancreatic hormone, insulin. Once inside, it is converted to energy or stored for future use. In diabetes, there is either a deficiency of insulin or a lack of sensitivity to its actions.
Approximately 18 million Americans are diabetic. Nearly one-third of these people do not realize that they are diabetic and therefore are not under treatment. The incidence of diabetes is growing with every year.
Diabetes is a disorder related to metabolism, or the way our bodies use digested food for growth and energy. Most of the food we eat is broken down by the digestive juices into a simple sugar called glucose. Glucose is the main source of fuel for the body. After digestion, the glucose passes into our bloodstream, where it is available for use by the body cells for growth and energy.
In order for the glucose to penetrate the body’s cells, insulin must be present. Insulin is a hormone produced by the pancreas, a large gland behind the stomach, in response to eating. The presence of insulin ensures that glucose can enter the body's cells and be converted into energy. When diabetes is present, insulin is absent or used inefficiently. Therefore, glucose remains in the bloodstream and is not used for energy.
Over time, high levels of glucose in the blood can cause damage to the heart, blood vessels, feet, nerves, eyes and kidneys. Proper treatment aimed at controlling blood glucose levels can help prevent these complications.
When we eat, the pancreas is supposed to automatically produce the right amount of insulin to move 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, overflows into the urine, and passes out of the body. 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, which was sometimes called Insulin-dependent diabetes mellitus (IDDM). This name is no longer favored, as many Type II patients come to need insulin.Type II diabetes, which was also formerly called 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 system for fighting infection (the immune system) turns against 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 percent 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 percent 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 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 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 percent higher in African Americans and 110 to 120 percent 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.