A serious disorder caused by an absence of or insufficient amount of insulin in the bloodstream.
Insulin is a hormone produced by the pancreas in varying amounts, depending on the concentration of glucose (sugar). When the pancreas is unable to secrete enough insulin to maintain a normal concentration of glucose in the blood, the blood-glucose concentration becomes elevated. Large amounts of glucose are then excreted in the urine. Insulin allows glucose to be absorbed by the liver and fat cells, where it is stored as glycogen. In times of stress, exercise, or an emergency, the glycogen is reconverted back to glucose. It also sends glucose to the muscle cells where it is then converted to energy.
More than 12 million Americans are affected by
diabetes. There is a 5-6% increase in the number of those affected each year by the disease, primarily due to the population's increased rate of longevity. A rising rate of obesity, a prime cause for incidences of diabetes over the age of 40, also contributes to the increasing frequency of diabetes. It is estimated that for each reported new case of diabetes, there is an unreported one because symptoms of the early stages of adult diabetes tend to go unrecognized. Symptoms usually progress from mild to severe as the disease progresses.
Approximately 300,000 deaths each year are attributed to diabetes. Its prevalence increases with age, from about 0.2% in persons under 17 years of age to about 10% in persons aged 65 years and over. Females have a higher rate of incidence for the disease, while higher income groups in the United States show a lesser incidence than lower income groups. The incident rate is markedly different among ethnic groups; it is 20% higher in non-Caucasians than in Caucasians. However, for reasons as yet unknown, the rate of diabetes in ethnic groups such as Native Americans, Latin Americans, and Asian Americans is especially high and continues to rise.
There are two forms of diabetes mellitus. Type I is called insulin-dependent and type II, non-insulin-dependent. (In June 1997, an Expert Committee of the American Diabetes Association recommended changing the categories of diabetes to Type 1 [formerly Type I-indulin-dependent diabetes mellitus] and Type 2 [formerly Type Il-non-insulin-dependent diabetes mellitus]. This essay uses the conventional terminology, which was widely used at the time of publication.)
Insulin-dependent diabetes (type I) generally starts in childhood, affects approximately 700,000 Americans, and is characterized by severe insulin deficiency. It is probably due to the destruction of the insulin-secreting cells of the pancreas, which is often caused by an autoimmune disorder. Without insulin, the person develops ketoacidosis, a condition where high levels of ketone bodies are present in the blood. When the body is deprived of glucose, which can occur as a result of insulin deprivation or fasting, the body begins to break down fat for fuel. Ketones are the result of this lipid metabolism. The resulting lowered blood pH value leads to the
acidosis.
Ketoacidosis is a serious condition and can lead to confusion, unconsciousness, and death if not treated. It can be diagnosed by urine tests which detect ketones in the urine. Untreated or uncontrolled diabetes will lead to ketosis, but fasting or starvation also produces ketones. Other symptoms of ketoacidosis include vomiting,
abdominal pain, loss of appetite, and nausea. A very high blood glucose level in insulin-dependent diabetes can also lead to
heart failure and
coma.
Genetics plays a major role in Type I diabetes. There is also some evidence that children infected with certain viruses—rubella and coxsackie B in particular—may be susceptible to the disease. Diabetes in newborns can result from low birth weight as well as genetic predisposition. Some infants experience temporary diabetes, which may recur later in life.
Non-insulin-dependent diabetes (type II) usually occurs in people over age 40, and affects approximately 15.3 million Americans. This group comprises about 80% to 85% of the diabetic population. Even though they may have more than normal levels of insulin, they are resistant to its action. Unlike those with type I diabetes, people with type II diabetes rarely have ketoacidosis. Instead, insulin action can be impaired by obesity. Therefore, people who gain too much weight and ethnic groups that have changed to higher carbohydrate diets appear to be particularly prone to type II diabetes.
Pregnancy can also elevate a woman's glucose level. This condition is known as
gestational diabetes and complicates approximately four percent of all U.S. pregnancies. Although their glucose levels may return to normal after they give birth, these woman may be at risk of developing type II diabetes in the future.
For those people who are in a high risk group for getting diabetes (those who have had relatives with diabetes, adults over the age of 40 who are
overweight, and women who have had babies weighing nine pounds or more at birth), there is a quick and simple screening test that requires a drop of blood from the finger and takes about one to two minutes to complete. The test shows if there is a high or low blood-sugar level in the blood. After the results of the screening test, other tests can be done, if necessary. If the screening test shows blood-sugar levels that are either too high or too low, a fasting plasma glucose test can be given. One or more samples of blood are taken after the individual fasts for 10 to 16 hours. Blood-glucose levels of less than 115 milligrams per decaliter (mg/dl) are normal. Fasting plasma glucose levels of more than 140 mg/dl indicate diabetes. The oral glucose tolerance test also starts with a fast but adds a glucose drink taken after the fasting plasma glucose is tested. It is followed by several other tests to determine blood glucose levels. There are other tests used to monitor the condition, including self-tests. The presence of circulating islet antibodies is a good predictor of insulin-dependent diabetes. Research is being done on
genetic tests to predict the risk of developing diabetes.
Deaths from ketoacidosis and diabetic coma have decreased over the years. However, long-term complications from diabetes began to increase as diabetics' life span increased. Some of these complications are kidney failure,
heart disease,
blindness, and nervous system disorders, all of which are believed to be the results of elevated blood-glucose levels. Today, glucose levels are controlled by injecting a rapidly absorbed insulin just before each meal. Added to this dosage, the slowly absorbed insulin can then be injected or pumped in by a prosthetic implant device between meals to maintain low insulin concentrations. The amounts required are determined by frequent blood-glucose measurements.
For overweight, non-insulin-dependent diabetics, controlling diet, avoiding foods high in sugar and carbohydrates, and encouraging weight loss may be sufficient treatment. A regular program of physical exercise is also recommended as an important part of diabetes treatment. Exercise utilizes surplus blood glucose and helps a person to both lose and maintain weight. In addition, non-insulin-dependent-type oral drugs may stimulate the pancreas to secrete additional insulin. It may be necessary to give injections of insulin.
Diabetes can be particularly difficult to manage during adolescence, when elevated levels of certain growth hormones make controlling blood glucose levels difficult. In addition, adolescents sometimes resist the dietary restrictions and close monitoring necessary to maintain good health. The most serious problem diabetic children face is
hypoglycemia, or low blood glucose. Common symptoms in young children include misbehavior and irritability, although symptoms can vary from episode to episode. Hypoglycemia is easily treated by eating a sweet food. Parents are advised to inform teachers about symptoms and to enlist their help in maintaining the routines necessary to manage diabetes, including frequent testing of blood glucose levels, eating snacks before exercise, careful diet, and close monitoring of insulin dosage.
A relatively new treatment for type II diabetes is the drug
Glucophage (generic name: metformin). Glucophage affects how the body handles its own insulin, increasing its effectiveness. With only a few side effects (diarrhea, nausea, bloating) that fade after the body adjusts to the medication, Glucophage offers an alternative to those who don't respond to changes in diet and exercise