Causes and Symptoms (Magill’s Medical Guide, Sixth Edition)
Diabetes mellitus is by far the most common of all endocrine (hormonal) disorders. The word “diabetes” is derived from the Greek word for “siphon” or “running through,” a reference to the potentially large urine volume that can accompany the condition. Mellitus, the Latin word for “honey,” was added when physicians began to make the diagnosis of diabetes mellitus based on the sweet taste of the patient’s urine. The disease has been depicted as a state of starvation in the midst of plenty. Although there is plenty of sugar in the blood, without proper insulin action the sugar does not reach the cells that need it for energy. Glucose, the simplest form of sugar, is the primary source of energy for many vital functions. Deprived of glucose, cells starve and tissues begin to degenerate. The unused glucose builds up in the bloodstream, which leads to a series of secondary complications.
The most common symptoms of diabetes mellitus are related to hyperglycemia, glycosuria, and ketoacidosis. The acute symptoms of diabetes mellitus are all attributable to inadequate insulin action. The immediate consequence of an insulin insufficiency is a marked decrease in the ability of muscle, liver, and adipose (fat) tissue to remove glucose from the blood. In the presence of inadequate insulin action, a second problem manifests itself. People with diabetes continue to make the hormone glucagon. Glucagon, which...
(The entire section is 1386 words.)
Show us the love and view this for free! Use the facebook like button, or any other share button on this page, and get this content free!free!
Treatment and Therapy (Magill’s Medical Guide, Sixth Edition)
Insulin is the only treatment available for type 1 diabetes, and in many cases it is used to treat individuals with type 2 diabetes. Insulin is available in many formulations, which differ in respect to the time of onset of action, activity, and duration of action. Insulin preparations are classified as fast-acting, intermediate-acting, and long-acting; the effects of fast-acting insulin last for thirty minutes to twenty-four hours, while those of long-acting preparations last from four to thirty-six hours. Some of the factors that affect the rate of insulin absorption include the site of injection, the patient’s age and health status, and the patient’s level of physical activity. For a person with diabetes, however, insulin is a reprieve, not a cure.
Because of the complications that arise from chronic exposure to glucose, it is recommended that glucose concentrations in the blood be maintained as close to physiologically normal levels as possible. For this reason, it is preferable to administer multiple doses of insulin during the day. By monitoring plasma glucose concentrations, the diabetic person can adjust the dosage of insulin administered and thus mimic normal concentrations of glucose relatively closely. Basal concentrations of plasma insulin can also be maintained throughout the day by means of electromechanical insulin delivery systems. Whether internal or external, such insulin pumps can be programmed to...
(The entire section is 1288 words.)
Show us the love and view this for free! Use the facebook like button, or any other share button on this page, and get this content free!free!
Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
Diabetes mellitus is a disease of ancient origin. The first written reference to diabetes, which was discovered in the tomb of Thebes in Egypt (1500 b.c.e.), described an illness associated with the passage of vast quantities of sweet urine and an excessive thirst.
The study of diabetes owes much to the Franco-Prussian War. In 1870, during the siege of Paris, it was noted by French physicians that the widespread famine in the besieged city had a curative influence on diabetic patients. Their glycosuria decreased or disappeared. These observations supported the view of clinicians at the time who had previously prescribed periods of fasting and increased muscular work for the treatment of the overweight diabetic individual.
It was Oscar Minkowski of Germany who, in 1889, accidentally traced the origin of diabetes to the pancreas. Following the complete removal of the pancreas from a dog, Minkowski’s technician noted the animal’s subsequent copious urine production. Acting on the basis of a hunch, Minkowski tested the urine and determined that its sugar content was greater than 10 percent.
In 1921, Frederick Banting and Charles Best, at the University of Toronto in Canada, successfully extracted the antidiabetic substance “insulin” using a cold alcohol-hydrochloric acid mixture to inactivate the harsh digestive enzymes of the pancreas. Using this substance, they first controlled the disease in a...
(The entire section is 690 words.)
Show us the love and view this for free! Use the facebook like button, or any other share button on this page, and get this content free!free!
For Further Information: (Magill’s Medical Guide, Sixth Edition)
American Diabetes Association. “Gestational Diabetes.” Diabetes Care 26 (2003): S103-S105. Discussion of gestational diabetes risk factors, diagnosis, and treatment.
_______. http://www.diabetes.org. Comprehensive information on both type 1 and type 2 diabetes and current research and scientific findings, provides community forums and news stories, and helps decipher health insurance issues, among other features.
American Diabetes Association Complete Guide to Diabetes. 4th rev. ed. Alexandria, Va.: American Diabetes Association, 2006. A comprehensive consumer guide for all issues surrounding diabetes.
Becker, Gretchen. The First Year—Type 2 Diabetes: An Essential Guide for the Newly Diagnosed. 2d ed. New York: Marlowe, 2007. A unique guide for persons with type 2 diabetes, setting expectations and answering questions related to the first week of diagnosis, the first months, and the first year. Topics include treatment options, dietary choices, and holistic alternatives.
Centers for Disease Control and Prevention. http://www.cdc.gov/diabetes/consumer. A concise overview of diabetes—its diagnosis, treatment, and prevention.
Children with Diabetes. http://www.childrenwith diabetes.com. Site provides information that helps children with diabetes and their families learn about the disease, meet people with diabetes, and help others with diabetes....
(The entire section is 364 words.)
Diabetes Mellitus (Encyclopedia of Medicine)
Diabetes mellitus is a condition in which the pancreas no longer produces enough insulin or when cells stop responding to the insulin that is produced, so that glucose in the blood cannot be absorbed into the cells of the body. Symptoms include frequent urination, lethargy, excessive thirst, and hunger. The treatment includes changes in diet, oral medications, and in some cases, daily injections of insulin.
Diabetes mellitus is a chronic disease that causes serious health complications including renal (kidney) failure, heart disease, stroke, and blindness. Approximately 14 million Americans (about 5% of the population) have diabetes. Unfortunately, as many as one-half are unaware that they have it.
Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin bonds to a receptor site on the outside of cell and acts like a key to open a doorway into the cell through which...
(The entire section is 4181 words.)
Diabetes Mellitus (Encyclopedia of Science)
Diabetes mellitus is a disease caused by the body's inability to use the hormone insulin. Insulin is normally produced in the pancreas, a gland attached to the small intestine. Its function is to convert carbohydrates into glucose. Glucose (also known as blood sugar) is the compound used by cells to obtain the energy they need to survive, reproduce, and carry out all their normal functions.
When cells are unable to use glucose for these functions, they use fat instead. One product of the metabolism of fats is a group of compounds known as ketones. Ketones tend to collect in the blood and disrupt brain functions.
Common signs of diabetes are excessive thirst, urination, and fatigue. The long-term effects of diabetes include loss of vision, decreased blood supply to the hands and feet and pain. If left untreated, diabetes can produce coma and cause death.
Two types of diabetes mellitus are known. Type I diabetes is also called juvenile or insulin-dependent diabetes. Type I diabetes occurs when the pancreas fails to produce enough insulin. Type II diabetes is also called adult-onset or noninsulin-dependent diabetes. Type II diabetes results when the pancreas does produce insulin but, for some reason, the body is unable to use the insulin normally. Type I diabetes can usually be controlled by doses of insulin and a...
(The entire section is 657 words.)
Diabetes Mellitus (Encyclopedia of Children's Health)
Diabetes mellitus is a chronic disease in which the body is not able to correctly process glucose for cell energy due to either an insufficient amount of the hormone insulin or a physical resistance to the insulin the body does produce. Without proper treatment through medication and/or lifestyle changes, the high blood glucose (or blood sugar) levels caused by diabetes can cause long-term damage to organ systems throughout the body.
There are three types of diabetes mellitus: type 1 (also called juvenile diabetes or insulin-dependent diabetes), type 2 (also called adult-onset diabetes), and gestational diabetes. While type 2 is the most prevalent, consisting of 90 to 95 percent of diabetes patients in the United States, type 1 diabetes is more common in children. Gestational diabetes occurs in pregnancy and resolves at birth.
Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (primarily sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. However, glucose requires insulin in order to be processed for...
(The entire section is 4766 words.)
Diabetes Mellitus (Encyclopedia of Alternative Medicine)
Diabetes mellitus is a condition in which the pancreas no longer produces enough insulin or when cells stop responding to the insulin that is produced, so that glucose in the blood cannot be absorbed into the cells of the body. Symptoms include frequent urination, tiredness, excessive thirst, and hunger.
Diabetes mellitus is a chronic disease that causes serious health complications including renal (kidney) failure, heart disease, stroke, and blindness. Approximately 14 million Americans (about 5% of the population) have diabetes. Unfortunately, as many as one-half of them are unaware that they have it.
Every cell in the human body needs energy in order to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates (sugars and starches). Glucose from the digested food circulates in the blood as a ready energy source for cells. Insulin is a hormone or chemical produced by cells in the pancreas, an organ located behind the stomach. Insulin binds to receptor sites on the outside of cells and acts like a key to open a door-way...
|SYMPTOMS OF DIABETES MELLITUS|
(The entire section is 4292 words.)
Diabetes Mellitus (Encyclopedia of Nursing & Allied Health)
Diabetes mellitus is a condition that occurs when either the pancreas does not produce enough insulin or the body's cells stop responding to the insulin that is produced. In either case, glucose in the blood cannot be absorbed or used by the cells of the body.
Diabetes has been recognized as a disease since ancient times. Egyptian papyri described its symptoms in 1550 B.C., and Hindu physicians noted 500 years later that insects were drawn to the sugary urine of people afflicted with diabetes. The disease was first named in 230 B.C. by Apollonius of Memphis, who took it from the Greek diabainein (to pass through), a description of the unquenchable thirst and copious urine produced by diabetics. It was not until the latter part of the eighteenth century that the British physician John Rollo appended the Latin term mellitus (honey-sweet) to distinguish diabetes from other diseases that caused excessive urine production.
Diabetes mellitus is a chronic disease that causes serious health complications including renal failure, heart disease, stroke, blindness, and peripheral neuropathy with vascular insufficiency, putting patients at risk for gangrene and subsequent amputation of the extremities. Approximately 16 million Americans have diabetes; of these, it is estimated that around 5.4 million are undiagnosed. Diabetes afflicts 120 million people worldwide, with the World Health Organization predicting that the number will reach 300 million by 2025.
Every cell in the human body requires fuel to function. The body's primary energy source is glucose, a simple sugar resulting from the digestion of foods containing carbohydrates. Glucose from the digested food circulates in the blood as a ready energy source for any cells that need it. Insulin is a protein hormone secreted into the blood by cells in the pancreas called islets of Langerhans. Insulin bonds to a receptor site on the outside of a cell, and acts like a key to open a doorway into the cell through which glucose can enter. The liver may convert excess glucose to concentrated energy sources like glycogen or fatty acids, which are stored for later use. If there is insufficient insulin production, or when the doorway no longer recognizes the insulin key, glucose stays in the blood rather than entering the cells.
As the level of glucose in the blood rises, a condition called hyperglycemia results. The body will try to dilute this high blood glucose level by drawing water out of the cells, pumping it into the bloodstream, and excreting it in urine. It is not unusual for those with undiagnosed diabetes to complain of constant thirst, to drink large quantities of fluids, and to urinate frequently as their bodies attempt to get rid of the extra glucose.
At the same time that the body is attempting to rid itself of glucose in the blood, its cells are starving for glucose and sends signals to eat more food, giving patients tremendous appetites. To provide energy for the starving cells, the body also tries to convert fats and proteins into glucose. Breaking down these substances causes acid compounds called ketones to form in the blood and to be excreted in the urine. As ketones build up in the blood, a condition called ketoacidosis can occur. If left untreated, this condition can be life threatening, eventually leading to coma and death.
Types of diabetes mellitus
Type 1 diabetes, sometimes called juvenile diabetes, commonly begins in childhood or adolescence. It occurs more frequently in populations descended from northern European countries than in those from southern Europe, the Middle East, or Asia. This form of diabetes is also called insulin-dependent diabetes because people who develop it need to have insulin injections at least once a day. In this form of diabetes, the body produces little or no insulin. Its onset is sudden, and it usuallyut not alwaysccurs in people under 30.
Brittle diabetics are a subgroup of type 1 in which patients have frequent and rapid blood sugar level swings, alternating between hyper-and hypoglycemia. These patients may need several injections of different types of insulin taken at specific times during the day to maintain a blood glucose level within a fairly normal range.
The more common form of diabetes is type 2, sometimes called age-onset or adult-onset diabetes. It accounts for more than 90% of all diabetes in the United States. This form occurs most often in people who are over 50, as well as those who are overweight and sedentary; it is also more common in people of Native American, Hispanic, and African-American descent. People who have migrated to Western cultures from East India, Japan, and Australian Aboriginal cultures are also more likely to develop type 2 diabetes than those who remain in their native countries.
Type 2, also called noninsulin-dependent diabetes, is considered a milder form of diabetes because of its gradual onset (sometimes developing over the course of several years) and because it can often be controlled with diet and oral medication. The consequences of uncontrolled and untreated type 2 diabetes, however, are as serious as those caused by type 1. Many people with type 2 diabetes are able to control their blood glucose with diet and oral medications, but for those who cannot, insulin injections may be necessary. In recent years, an alarming trend was being noted in Western culture, particularly in the United States: a tendency for children, teenagers, and young adults, particularly those who are obese, to develop this type of diabetes.
Another type of diabetes is gestational diabetes, which can develop during pregnancy and generally resolves after the delivery of the baby. This diabetic condition develops during the second or third trimester in approximately 2% of pregnancies. The condition is normally treated by diet, however, insulin injections may be required for periodic exacerbation control. Women who develop diabetes during pregnancy are at higher risk for developing type 2 diabetes within five to 10 years.
Diabetes may also develop as a result of or in concert with pancreatic disease, alcoholism, malnutrition, or other severe illnesses that tax the body's immune system.
Causes and symptoms
The causes of diabetes mellitus are unclear, however, there appear to be both hereditary and environmental factors involved. Research has shown that some people who develop diabetes have common genetic markers. In type 1 diabetes, the immune system is probably triggered by a virus or other microorganism that destroys the cells in the pancreas that produce insulin.
Type 2 diabetes is characterized by the insulin resistance syndrome, in which peripheral adipose and muscle cells fail to respond appropriately to circulating insulin, which the pancreas produces in response to food loads. Research has now shown that the insulin resistance syndrome is closely associated with dyslipidemia, an imbalance in the ratio of total cholesterol to the cholesterol fractions of either low-density lipoproteins (bad cholesterol) or to high-density lipoproteins (good cholesterol). Untreated or inadequately treated dyslipidemia leads to atherosclerosis and eventually to the microvascular complications mentioned above. Patients with type 2 diabetes and dyslipidemia are often treated with one of the drugs from the group known as statins, in addition to oral antidiabetic agents.
Age, obesity, and family history may all play a role in the development of type 2 diabetes. Symptoms may begin so gradually that a person may not be aware of them. Early signs are fatigue, extreme thirst, and frequent urination. Other symptoms may include sudden weight loss, slow wound healing, urinary tract infections, or blurred vision. It is not unusual for type 2 diabetes to be detected while a patient is seeing a doctor for another health concern that is actually being caused by the as-yetundiagnosed diabetes.
Individuals who are at high risk of developing type 2 diabetes mellitus include those who:
- Are obese (more than 20% above their ideal body weight).
- Have a primary relative (immediate family member) with diabetes mellitus.
- Belong to a high-risk ethnic population (African American, Native American, Hispanic, or Native Hawaiian).
- Have been diagnosed with gestational diabetes or have delivered a baby weighing more than 9 lbs (4 kg).
- Have been diagnosed with transient diabetes at the time of a moderate to severe systemic infection (like protracted pneumonia).
- Have high blood pressure (140/90 mm Hg or above).
- Have a high-density lipoprotein cholesterol level less than or equal to 35 mg/dL and/or a triglyceride level greater than or equal to 250 mg/dL.
- Have had impaired glucose tolerance or impaired fasting glucose on previous testing.
Several common medications can impair the body's use of insulin, causing a condition known as secondary diabetes. These medications include treatments for high blood pressure (furosemide, clonidine, and thiazide diuretics), drugs with hormonal activity (oral contraceptives, thyroid hormone, progestins, and systemic gluococorticoids), and the anti-inflammation drug indomethacin. Several drugs used to treat mood disorders can also impair glucose absorption. These drugs include haloperidol, lithium carbonate, phenothiazines, tricyclic antidepressants, and adrenergic agonists. Other medications that can cause diabetes symptoms include isoniazid, nicotinic acid, cimetidine, and heparin.
Symptoms of diabetes can develop suddenly (over days or weeks) in previously healthy children or adolescents, or can develop gradually (over several years) in overweight adults past the age of 40. The classic symptoms include fatigue, frequent urination, excessive thirst, excessive hunger, tingling of hands and feet, pruritus, and weight loss. In sudden-onset diabetes, some patients may have a "fruity" odor to their breath.
Ketoacidosis, a condition that results from starvation or uncontrolled diabetes, is common in patients with type 1 diabetes. Its symptoms include abdominal pain, vomiting, tachypnea, and extreme fatigue or lethargy. Patients with ketoacidosis will also have a characteristically sweet, fruity breath odor. Left untreated, this condition may lead to coma and death.
With type 2 diabetes, the condition may not become evident until the patient presents for medical treatment for some other condition. A patient may have heart disease, chronic infections of the gums and urinary tract, blurred vision, numbness in the feet and legs, and slowly healing wounds. Women may experience genital itching.
Diabetes is suspected based on symptoms, but many of its symptoms may also suggest other diseases. Urine tests can begin the winnowing process that leads to a definitive diagnosis. Urine tests can detect ketones and protein in the urine; they can also show urine "spill," the renal threshold at which the kidneys will spill excess blood sugar into the urine. They can help assess how adequately the kidneys are functioning, and are used to monitor the disease once the patient is compliant with the recommended diet, oral medications, or insulin.
Although urine tests can confirm an initial suspicion of diabetes, specific blood tests are often required to make the differential diagnosis. One such diagnostic tool is the fasting glucose test. Blood is drawn via a venipuncture after a period of at least eight hours of fasting, usually in the morning prior to breakfast. The red blood cells are separated from the sample and the amount of glucose is measured in the remaining plasma. A plasma level of 7.8 mmol/L (200 mg/L) or greater can indicate diabetes. The fasting glucose test is usually repeated on another day to confirm the results. A postprandial glucose test involves taking blood one to two hours after the patient has eaten a meal.
A glucose tolerance involves blood and urine sampling over a three-or five-hour period after a patient drinks a specially prepared syrup of glucose and other sugars. During the test the patient drinks no other fluids. When patients are healthy, the blood glucose level rises immediately after the drink and then decreases gradually as insulin is used by the body to metabolize the glucose. In patients with diabetes, the serum glucose rises and stays elevated after drinking the sweetened liquid. A plasma glucose level of 11.1mmol/L (200 mg/dL) or higher two hours after drinking the syrup and at one other point during the two-hour test period confirms the diagnosis of diabetes. During this time, the urine is tested for glucose spill.
A diagnosis of diabetes is confirmed if there are symptoms of diabetes and a blood glucose level of at least 11.1 mmol/L, a fasting plasma glucose level of at least 7 mmol/L, or a two-hour plasma glucose level of at least 11.1 mmol/L during an oral glucose tolerance test.
Monitoring glucose levels
The blood test that gives the best indication of average blood glucose levels over time is the hemoglobin A1C (HbA1C) test. It measures the percentage of hemoglobin A that has become glycosylated (coated with glucose) during the past three months. (Red blood cells have a life span of about 100 days; after that they are recycled by the bone marrow.) A normal reading for healthy individuals is about of 4% glycosylated HbA1C. Diabetics whose disease is well controlled will read 7% or lower. A reading of 8% or higher indicates the need for a change in treatment or better dietary compliance; these patients are also at increased risk for such complications as eye disease, kidney disease, and nerve damage. The HbA1C test should be performed at least twice a year to be sure that blood glucose levels stay within safe and healthy levels.
Home blood glucose monitoring kits are available so patients with diabetes can monitor their daily glucose readings. For decades, a small needle or lancet was used to prick the finger and a drop of blood was collected and analyzed by a monitoring device. Modern blood monitoring devices, however, are strapped on like a wrist watch; no finger sticks are required. This is especially helpful for patients who need to test their blood glucose levels several times during the day.
There is no cure for diabetes; it can, however, be controlled so that patients can live a relatively normal life. Treatment focuses on two goals: keeping blood glucose readings within a normal range (140 mg/dL, the standard accepted by the American Diabetes Association) and preventing the development of long-term complications. Careful monitoring of diet, exercise, and blood glucose levels are important, affecting the need for insulin replacement as well as the dose of oral antidiabetic agents. Lack of consistent control leads to complications of the disease.
Diet and moderate exercise are the first treatments implemented in diabetes. For many type 2 diabetics, weight loss may be an especially important part of treatment. A well balanced, nutritious diet provides approximately 50% to 60% of calories from carbohydrates, around 10% to 20% from protein, and less than 30% of calories from fat. The number of calories required by an individual depends on their age, weight, and activity level. Calorie intake also needs to be distributed over the course of the entire day so that surges of glucose entering the blood are kept to a minimum. The timing of snacks must also correspond to the timing and type of insulin being used.
Counting the calories in different foods can be complicated, so patients are usually advised to consult a nutritionist, who will set up an individualized, easily managed diet for each patient. Both the American Diabetes Association and the American Dietetic Association recommend diets based on the use of food-exchange lists. Each food-exchange unit contains a known amount of calories in the form of protein, fat, or carbohydrate. A patient's diet plan will allow a certain number of exchanges from each food category (meat or protein, fruits, breads and starches, vegetables, and fats) to be eaten at mealtimes and as snacks. Patients can choose which foods they eat as long as they stick with the number of exchanges prescribed and adhere to their schedule if they take a combination of insulin types. The food exchange system, along with an exercise program, can help patients lose excess weight and improve their overall health. This may be especially important for type 2 diabetics.
A variety of oral medications are available to help lower blood glucose in type 2 diabetics. They act in a variety ways to control postprandial (after meal) glucose levels; the particular medication or combination of drugs chosen will be based largely on the individual patient profile. Some oral medications stimulate the pancreatic beta cells to produce additional insulin. Others change the way receptors on peripheral adipose (fat) and muscle cells receive the insulin and act on it, and still others block the intestinal absorption of food byproducts that would increase blood glucose levels.
All drugs have side effects that may make them inappropriate for particular patients. For example, some medications may stimulate weight gain or cause stomach irritation, so they may not be the best treatment for individuals who are already overweight or who have stomach ulcers. While these medications are an important aspect of treatment for type 2 diabetes, they are not a substitute for an appropriate diet and exercise. Oral medications are not effective for type 1 diabetes, in which the patient produces little or no insulin.
Patients with type 1 diabetes need daily injections of insulin to help their bodies utilize glucose. The amount and type of insulin required depends on the individual patient's height, weight, age, food intake (quantity and timing), and activity level. Some patients with type 2 diabetes may need to use insulin injections if their diabetes cannot be controlled with diet, exercise, and oral medication. Injections are given subcutaneously, using a small needle and syringe. Injection sites can be anywhere on the body where there is adequate subcutaneous tissue, including the upper arm, abdomen, hips, or upper thigh.
Purified human insulin is most commonly used, however, insulin from beef and pork sources is also available. Insulin may be given as an injection of a single dose of one type of insulin once a day. Different types of insulin (short-acting rapid-onset, slow-onset long-acting) can be mixed and given in one dose or split into two or more doses during the day. Patients that require multiple injections over the course of a day may be able to use an insulin pump that administers small doses of insulin on demand. The small battery-operated pump is worn outside the body and is connected to a tube that is inserted into the abdomen. Pumps can be programmed to inject small doses of insulin at various times during the day, or the patient may be able to adjust the insulin doses to coincide with glucometer readings, meals, and exercise. There are also multiple-dose insulin injection devices available that are commonly referred to as insulin pens. They are designed to hold a cartridge containing several days' worth of insulin dosages.
Regular human insulin is fast-acting and begins to work within 150 minutes; its peak glucose-lowering effect occurs about two hours later and its effects last approximately 4 hours. Neutral protamine Hagedorn (NPH) and Lente insulin are intermediate-acting insulins that start to work within 4 hours, and last 186 hours. Ultralente is a long-acting form of insulin that starts to work within four to eight hours and lasts 28 to 36 hours. Many diabetics combine a long-or intermediate acting insulin with a short-acting one to provide the proper insulin peak at mealtimes. Premixed insulins are available in standard doses. Newer forms of insulin are under investigation.
Although the goal of most diabetes treatment is to lower blood glucose levels, hypoglycemia, or low blood glucose, can be caused by too much insulin, too little food, alcohol consumption, or increased exercise. A patient with symptoms of hypoglycemia may be hungry, irritable, confused, and tired. The patient may be diaphoretic (sweating profusely), pale, and shaky. Left untreated, the patient can lose consciousness or have a seizure soon after these symptoms appear. This condition, called an insulin reaction or insulin shock, should be treated by giving the conscious patient something with readily available sugar to eat or drink like orange juice, hard candy, or sugar cubes. If the patient has declined into unconsciousness, do not try to feed them. This is a critical condition and always requires emergency intravenous therapy.
Transplantation of healthy pancreatic tissue into a diabetic patient can be successful. However, it is not clear if the potential benefits outweigh the risks of the surgery and drug therapy required.
Since uncontrolled diabetes can be life-threatening if not properly managed, patients should be instructed to not attempt treatments without medical supervision. Patients interested in alternative and herbal remedies should be instructed about the possible benefits, but cautioned to consult with a health care professional before they try them. Some alternative therapies may interact negatively with some of the oral antidiabetic agents or other drugs, such as antihypertensives or anticoagulants.
Diabetic peripheral neuropathyondition in which the sensitivity of nerves to pain, temperature, and pressure is dulled, particularly in the legs and feet.
Diabetic retinopathy condition in which the tiny blood vessels to the retina are damaged, leading to blurred vision, sudden blindness, or black spots, lines, or flashing light in the field of vision.
Hemoglobin Aormal hemoglobin found in the blood of an adult.
Hemoglobin A1Cne of three fractions of hemoglobin A; the other two are HBA1a and HbA1b. Because HbA1c can become glycosylated, it is an important measure of blood glucose over the past three months.
Hyperglycemiabnormally high levels of blood glucose.
Hypoglycemiabnormally low levels of blood glucose.
Ketoacidosisondition that results in untreated diabetes from the body's attempt to burn fat for fuel when carbohydrates cannot be utilized. Ketones, the byproduct of fat metabolism, enter the bloodstream and make the blood more acidic than the body's tissues.
For patients who are willing to consult with their physician, alternative options may include:
- Fenugreek has been shown in some studies to reduce blood insulin and glucose levels while also lowering cholesterol.
- Bilberry may lower blood glucose levels, as well as help to maintain healthy blood vessels.
- Garlic may lower blood sugar and cholesterol levels.
- Cayenne pepper may help relieve the pain of diabetic neuropathy.
Any therapy that lowers stress levels may also be useful in treating diabetes by helping to reduce insulin requirements. Among the alternative treatments that aim to lower stress are hypnotherapy, biofeedback, and meditation.
Uncontrolled diabetes is a leading cause of blindness, end-stage renal disease, and peripheral vascular insufficiency, which leads to limb amputations. It also doubles the risks of heart disease and increases the risk of stroke. Eye problems including cataracts, glaucoma, and diabetic retinopathy are also more common in diabetics.
Diabetic peripheral neuropathy is a condition where nerve endings, particularly in the legs and feet, become less sensitive. Diabetic foot ulcers are a particular problem since the patient does not feel the pain of a blister, callous, or other minor injury. Poor blood circulation in the legs and feet contribute to delayed wound healing. The inability to sense pain along with the complications of delayed wound healing can cause minor injuries, blisters, or calluses to become infected and difficult to treat. In cases of severe infection, the infected tissue begins to break down and rot away. The severe infection may further exacerbate diabetes and increase blood glucose levels, perpetuating the problem. In the most serious infection cases, toes, feet, or legs may need to be amputated.
Diabetes can also affect the kidneys, a condition called diabetic nephropathy. This usually means that soft kidney tissue hardens and thickens, a process called sclerosis; this is especially true for the glomerulus (kidney membrane), which filters protein and other waste products from the blood. The ADA estimates that 355% of type 1 patients and 200% of type 2 patients have damaged kidneys. Because the symptoms of nephropathy may not appear until 80% of kidney function is gone, periodic tests of kidney function are especially important for patients with diabetes. Once renal function drops to 105%, kidney dialysis or a kidney transplant become necessary.
The risk of heart disease for patients with diabetes is two to four times higher than that of the general population. Death from heart disease is also two to four time higher in diabetics, as is the risk of stroke. These statistics hold for people with both type 1 and type 2 diabetes. The risk of cardiovascular disease increases with age, obesity, smoking, poor blood glucose control, and family history of heart disease.
Health care team roles
All members of the health care team may come into contact with diabetic patients. The nurse plays a particularly important role in teaching patients the skills necessary to manage this complex disease, and educating them about the effects of their medications.
Research continues on ways to prevent diabetes and to detect those at risk for developing the disease. While the onset of type 1 diabetes is unpredictable, the risks for developing type 2 diabetes can be reduced by maintaining a healthy weight and exercising regularly. The physical and emotional stresses of surgery, illness (especially systemic infection), pregnancy, and alcoholism can all increase the risks for diabetes, so maintaining a healthy lifestyle is critical to preventing the onset of type 2 diabetes and further complications. Research is in progress to determine the usefulness of placing high-risk patients on metformin (Glucophage; an oral antidiabetic drug used to treat type 2 diabetes) prophylactically in an effort to delay or prevent the onset of type 2 diabetes.
Beers, Mark H., and Robert Berkow. The Merck Manual of Diagnosis and Therapy. 17th ed. Whitehouse Station, NJ: Merck and Company, Inc., 1999.
Lincoln, Thomas A. "A1c: Know Your Value!" Diabetes Forecast (March 2001): 66.
Pennachio, Dorothy L. "How to Manage Diabetes in the Older Patient." Patient Care (January 30, 2001): 53.
American Diabetes Association. 1701 North Beauregard Street, Alexandria, VA 22311. 800-DIABETES. <<a href="http://www.diabetes.org">http://www.diabetes.org>.
Juvenile Diabetes Foundation International. 120 Wall Street, New York, NY 10005-4001. 800-JDF-CURE. <<a href="http://www.jdf.org">http://www.jdf.org>.
American Diabetes Association. Clinical Practice Recommendatons. "Tests of Glycemia in Diabetes" Position Statement. Diabetes Care 24, no. 1. <<a href="http://journal.diabetes.org/FullText/Supplements/DiabetesCare/Supplement101/S80.htm">http://journal.diabetes.org/FullText/Supplements/DiabetesCa... >.
Diabetes Manager. "History of Diabetes." <<a href="http://www.diabetesmanager.com/Education/Articles/Basics/history.html">http://www.diabetesmanager.com/Education/Articles/Basics/hi... >.
Kentucky Department for Public Health. "The Hemoglobin A1C Test: The Best Test For Blood Sugar Control." <<a href="http://publichealth.state.ky.us/diabetes-hemoglobin_a1c_test.htm">http://publichealth.state.ky.us/diabetes-hemoglobin_a1c_tes... >.
Moran, David T. "Glycosylated hemoglobin." <<a href="http://www.healthanswers.com/library/MedEnc/enc/1273.asp">http://www.healthanswers.com/library/MedEnc/enc/1273.asp>.
Deanna M. Swartout-Corbeil, R.N.
Diabetes Mellitus (Encyclopedia of Public Health)
The term "diabetes mellitus" represents a group of conditions characterized by abnormally high blood glucose levels (hyperglycemia). In 1997, nearly 16 million people in the United States had diabetes; approximately 10.3 million were diagnosed with the conditions, while an estimated 5.4 million were undiagnosed. Diabetes may be complicated by uncontrolled hyperglycemia, and treated diabetes may be complicated by abnormally low blood glucose levels (hypoglycemia). Maternal diabetes is associated with an increased incidence of major birth defects. Over time, diabetes may cause complications involving the eyes (retinopathy), kidneys (nephropathy), and nerves (neuropathy). Diabetes is also associated with an increased incidence of cardiovascular disease, including stroke, heart attack, and peripheral vascular disease. In the United States today, diabetes is a leading cause of birth defects, blindness, kidney failure, and nontraumatic leg amputations. It is also a major contributor to cardiovascular disease. Diabetes is the seventh leading cause of death in the United States, and medical care for people with diabetes is estimated to cost over $100 billion per year.
When diabetes is associated with marked hyperglycemia, it produces characteristic symptoms and signs; particularly increased thirst (polydipsia), increased urination (polyuria), and unexplained weight loss. At other times, hyperglycemia sufficient to cause changes in the eyes, kidneys, and nerves, and to increase the risk of cardiovascular disease, may be present without clinical symptoms. During this asymptomatic period, an abnormality in glucose metabolism may be demonstrated by measuring fasting venous glucose or venous glucose after an oral glucose challenge.
When a patient is symptomatic and the plasma glucose is unequivocally elevated, a diagnosis of diabetes presents no difficulty. When a patient is without clinical symptoms, a diagnosis of diabetes is more difficult. According to a 1997 American Diabetes Association (ADA) report, there are three ways to diagnose diabetes (see Table 1). All require measurement of venous plasma glucose, and each must be confirmed on a subsequent day by any one of the three methods. In general, the oral glucose tolerance test is not recommended for routine clinical use and is performed only in patients with elevated but nondiagnostic fasting plasma-glucose levels with a high index of suspicion for diabetes.
Once a diagnosis of diabetes mellitus is established, it is necessary to differentiate the various forms of the syndrome. Prior to 1979, diabetes was
|Criteria for the Three Methods Diagnosis of Diabetes Mellitus in Nonpregnant Adults|
|* In the absence of unequivocal hyperglycemia with acute metabolic decompensation, these criteria should be confirmed by repeat testing on a different day. The third measure (OGTT) is not recommended for routine clinical use.|
|SOURCE: Expert Committee on the Diagnosis and Classification of Diabetes Mellitus: Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus (1997). Diabetes Care 20:1183-1197.|
classified on the basis of age at diagnosis as either juvenile-onset diabetes mellitus (JODM) or adult-onset diabetes mellitus (AODM). In the late 1970s and early 1980s, a new classification system recognized two major forms of diabetes: insulin-dependent diabetes mellitus (IDDM or type I diabetes) and non-insulin-dependent diabetes mellitus (NIDDM or type II diabetes). In 1997, the American Diabetes Association recommended modifications to this classification system that eliminated the terms "insulin-dependent diabetes mellitus" and "non-insulin-dependent diabetes mellitus" and their acronyms. The terms "type 1" and "type 2" were retained, with Arabic numerals replacing the Roman numerals. Other specific types of diabetes were also recognized.
Type 1 diabetes is caused by pancreatic beta cell (B-cell) destruction. Immune-mediated type 1 diabetes results from cell-mediated autoimmune destruction of the B-cells of the pancreatic islets. This type of diabetes also has strong genetic or human leukocyte antigen (HLA) associations that can be either predisposing or protective. Another form of type 1 diabetes, termed "idiopathic" type 1 diabetes, is strongly inherited but lacks immunologic evidence for B-cell autoimmunity and is not HLA-associated. Most patients with
|Incidence of Diagnosed Diabetes per 1,000 Population by Age, United States, 1994.|
|SOURCE: Centers for Disease Control and Prevention (1997). Diabetes Surveillance, 1997. Atlanta, GA: CDC.|
idiopathic type 1 diabetes are of African or Asian descent.
Type 1 diabetes accounts for approximately 5 percent of diagnosed diabetes in the United Statespproximately 500,000 Americans have type 1 diabetes. Type 1 diabetes commonly occurs in childhood and adolescence, but it can occur at any age. Patients with type 1 diabetes are prone to ketoacidosis (decompensated diabetes with hyperglycemia and presence of abnormal acids [ketones] in the blood). Many affected patients have no family history of diabetes. Although most patients with type 1 diabetes are lean when they are diagnosed, the presence of obesity is not incompatible with the diagnosis.
Type 2 diabetes is characterized by both impairment of insulin secretion and defects in insulin action. It is often unclear which abnormality is the primary cause of hyperglycemia. Although patients with this type of diabetes may have insulin levels that appear normal or elevated, insulin levels are always low relative to the elevated plasma glucose levels. Thus, insulin secretion is defective in these patients and insufficient to compensate for the degree of insulin resistance. Although the specific origin of type 2 diabetes is not known, autoimmune destruction of B-cells does not occur. Although type 2 diabetes is associated with a strong genetic predisposition, the genetics of this form of diabetes are complex and not clearly defined.
Type 2 diabetes accounts for approximately 95 percent of diagnosed diabetes in the United States (9.8 million cases), and for the vast majority of the cases of undiagnosed diabetes. The risk of type 2 diabetes increases with age, obesity, and physical inactivity. As such, it is often regarded as a disease associated with a modern Western lifestyle. Type 2 diabetes occurs more frequently in women with prior gestational diabetes and in individuals with hypertension and dyslipidemia. Affected patients often have a family history of diabetes. Type 2 diabetes is more common in African Americans, Hispanic Americans, and Native Americans than in non-Hispanic white Americans. Ketoacidosis seldom occurs spontaneously in type 2 diabetes, but it may arise in association with the stress of another illness. Approximately 70 percent of patients with type 2 diabetes are obese.
Large, prospective, randomized, controlled clinical trials in both type 1 and type 2 diabetes have demonstrated that normal or near-normal blood glucose control can delay or prevent the development of major birth defects and the development and progression of complications affecting the eyes, kidneys, and nerves. Accordingly, the goals for management for both type 1 and type 2 diabetes are to achieve glucose levels as close to the nondiabetic range as possible while minimizing the side-effects of treatment (hypoglycemia and weight gain).
In nondiabetic subjects, blood glucose levels are between 70 and 90 mg/dl (milligrams per deciliter) in the fasting state and rise to 120 to 140 mg/dl one to two hours after meals. These values reflect normal glucose tolerance. Average glucose levels may be assessed by measurement of glycosylated hemoglobin (hemoglobin A1c), is a measure of the average blood glucose level over the previous two to four months. In nondiabetic subjects, hemoglobin A1c is generally less than 6.1 percent, and in poorly controlled diabetic subjects, it may rise to 12 percent or higher.
In general, the goals of treatment are to achieve blood glucose and hemoglobin A1c levels as close to the nondiabetic range as possible with diet, physical activity, and medications.
Diet. In type 1 diabetes, diet is designed to provide adequate nutrients for growth and development and for the maintenance of ideal body weight. The recommended diet includes approximately 20 percent of daily calories from protein, 30 percent from fat, and 50 percent from complex carbohydrates. Simple sugars are limited to prevent excessive glucose excursions, and carbohydrate content is distributed into regular meals and
|Prevalence of diagnosed diabetes per 1,000 population by age, sex, and race, United States, 1994|
|From Centers for Disease Control and Prevention. Diabetes Surveillance, 1997. Atlanta, GA. U.S. Department of Health and Human Services, 1997.|
snacks so that a similar quantity of carbohydrate is consumed at approximately the same time each day.
In type 2 diabetes, caloric content is adjusted to achieve and maintain an ideal body weight or, in those who are obese, to produce gradual weight loss or at least weight maintenance. Dietary composition may also be adjusted in light of intercurrent conditions. For example, sodium may be restricted for patients with hypertension, and both total fat and saturated fat may be restricted for those with high cholesterol.
Exercise. Exercise lowers blood glucose and improves glucose tolerance in diabetics. Other benefits of exercise are reductions in LDL cholesterol and triglycerides levels, and improvements in HDL cholesterol, improvements in blood pressure, improved cardiovascular fitness, and an increased sense of well-being and quality of life. Because exercise may potentiate the hypoglycemic effect of injected insulin and may, paradoxically, result in elevated blood glucose levels and the rapid development of ketosis in type 1 diabetic patients in poor metabolic control, the goal of management in type 1 diabetes is to permit people to enjoy and participate safely in physical and sport activities. In type 2 diabetes, exercise is frequently prescribed as an adjunct to reduced-calorie diets for weight reduction and to improve insulin resistance.
Medications. Because patients with type 1 diabetes are absolutely insulin deficient, treatment requires insulin injections. Although one or two injections per day are often adequate to prevent symptoms of hyperglycemia, intensive therapy employing three or four insulin injections per day, or continuous subcutaneous insulin infusion, may be necessary to achieve near-normal glucose control.
Both oral medications and injected insulin are used for the treatment of type 2 diabetes. Four groups of oral agents are currently available: insulin secretagogues, which enhance nutrient-stimulated insulin secretion; the biguanides, which suppress abnormal glucose production by the liver; the thiazolidinediones, which reduce insulin resistance at the level of muscle and fat; and the alpha-glucosidase inhibitors, which slow the breakdown and absorption of carbohydrates and reduce postprandial glucose excursions. To the extent that these four groups of oral medications have different mechanisms of action, they can be used clinically in combination. When oral agents are ineffective in controlling hyperglycemia or achieving glycemic goals, insulin is added or substituted.
Self-monitoring of blood glucose is integral to modern diabetes therapy. A lancet is used to obtain a small drop of blood, which is placed on a reagent strip and inserted in a small battery-powered meter. The meter reports the blood glucose level in less than a minute. Results of self-monitoring of blood glucose are used to guide adjustments in diet, exercise, and medications, for the monitoring and treatment of hypoglycemia, and in the home management of intercurrent illness.
INCIDENCE AND PREVALENCE
The number of people developing diabetes and the number of people with diabetes are increasing worldwide. In 2000, it was estimated that 154 million persons, or 4.2 percent of the world's population, twenty years of age and older had diabetes. By the year 2025, it is estimated that nearly 300 million persons, or 5.4 percent of the world's population, twenty years of age and older will have diabetes. The major part of this increase will occur in developing countries due to the aging of the population and increasing urbanization (associated with increased body weight and decreased physical activity).
In 1994, there were 939,000 Americans newly diagnosed with diabetes, with a disproportionate number among the elderly and minority populations. The incidence of diagnosed diabetes was3.61 cases per 1,000 persons per year in 1994 (see Table 2).
In 1994, about 8 million persons in the United States (3.1 percent of the population) reported that they had diabetes. The prevalence of diagnosed diabetes increases with age (see Table 3).
Diabetes is the seventh leading cause of deaths in the United States. The highest death rates due to diabetes are observed in older Americans and in minority populations. Death certificates underestimate diabetes mortality because of underreporting of diabetes. Only about 10 percent of people with diabetes who die have diabetes listed as the underlying cause of death on their death certificates, and only about 40 percent have it listed anywhere on their death certificates. Diabetes was the underlying cause of death for approximately 57,000 Americans in 1994, and diabetes was recorded on the death certificate of approximately 182,000 Americans. In 1994, black women had the highest death rates due to diabetes, followed by white women and men. That same year, 44 percent of all diabetes-related deaths (80,000 deaths) had cardiovascular disease listed as the underlying cause. Of these deaths, approximately 60 percent were caused by ischemic heart disease and 15 percent by stroke.
COMPLICATIONS AND COMORBIDITIES ASSOCIATED WITH DIABETES
Diabetic Ketoacidosis (DKA). Ketoacidosis is an acute metabolic complication of diabetes associated with hyperglycemia, nausea, vomiting, abdominal pain, dehydration, ketonemia, and acidosis. In 1994, DKA was the primary diagnosis for 89,000 hospital discharges and a listed diagnosis for 113,000 hospital discharges. Clinical trials have demonstrated that improved education in self-management and improved access to care can prevent up to 70 percent of DKA hospitalizations.
Adverse Outcomes of Pregnancy. Each year in the United States, type 1 diabetes complicates approximately 7,000 pregnancies and type 2 diabetes complicates approximately 12,000 pregnancies. Up to 1,700 infants (9%) of mothers with pregnancies complicated by diabetes (in the U.S.) are born with birth defects affecting the brain, spinal cord, heart, kidneys, and skeleton. Clinical trials have demonstrated that with intensive glycemic control before conception and during the first trimester, the incidence of major birth defects may be reduced to 2 percent, the rate that occurs in infants of nondiabetic mothers.
Diabetic Eye Disease. Diabetes is the leading cause of new cases of legal blindness in Americans between twenty and seventy-four years of age. As many as 40,000 Americans become blind each year as a result of diabetes. In type 1 diabetes, most legal blindness is due at least in part to diabetic retinopathy. Timely diagnosis and appropriate laser treatment can prevent up to 90 percent of blindness due to diabetic retinopathy. In type 2 diabetes, cataract, glaucoma, and senile macular degeneration are more frequent causes of blindness.
Diabetic Kidney Disease. Diabetic nephropathy is characterized by hypertension, proteinuria, and progressive renal insufficiency. Diabetes is now the leading cause of end-stage renal disease (kidney failure requiring dialysis or kidney transplant for survival). In 1997, over 33,000 Americans developed end-stage renal disease due to diabetes. Early detection, aggressive blood pressure control, and treatment with angiotensin-converting enzyme inhibitors can reduce the progression of diabetic nephropathy by about 60 percent.
Amputations. Diabetic neuropathy, peripheral vascular disease, and infection predispose people with diabetes to gangrene and amputations. More than half of all nontraumatic lower extremity amputations (LEAs) occur in people with diabetes. In 1994, there were approximately 67,000 diabetes-related hospital discharges with LEA reported as a procedure in the United States. Clinical trials have demonstrated that early detection of insensitive and deformed feet and multidisciplinary foot-care programs can reduce the rate of amputation by more than 50 percent.
Cardiovascular Disease Cardiovascular disease (CVD) is the leading cause of morbidity and
|Incidence of hospital discharge for cardiovascular disease per 1,000 diabetic population by age and sex, United States, 1994|
|From Centers for Disease Control and Prevention. Diabetes Surveillance, 1997. Atlanta, GA. U.S. Department of Health and Human Services, 1997.|
mortality in people with diabetes. Stroke, heart attack, and peripheral vascular disease are two to four times more common in people with diabetes than in people without diabetes. In 1994, there were 1,144,000 diabetes-related hospital discharges that had CVD listed as the primary discharge diagnosis (see Table 4). Part of the increased incidence of cardiovascular disease in people with diabetes is due to the greater prevalence of cardiovascular risk factors, including hypertension, dyslipidemia, and cigarette smoking. Clinical trials have demonstrated that pharmacologic treatments for hypertension and dyslipidemia are as effective, if not more effective, in people with diabetes compared to people without diabetes.
COSTS OF DIABETES
Health care costs incurred by people with diabetes include non-diabetes-related and diabetes-related costs. In the United States, in 1992, the direct cost of non-diabetes-related and diabetes-related medical care incurred by people with diabetes was estimated to be $105.2 billion. The direct cost of medical care attributable to diabetes was estimated to be $45.2 billion and the indirect cost of diabetes was estimated to be $46.6 million (see Table 5).
In 1992, per capita health care expenditures for people with diabetes averaged $9,493, compared to $2,604 for people without diabetes. When adjusted for age, per capita health care expenditures for people with diabetes were approximately
|Costs of diabetes mellitus in the United States, 1992 ($ billion)|
|Type of Cost||Setting||Attributable to diabetes*||Among People with diabetes**|
|*From Fox-Ray N, Wills S, Thamer M: Direct and Indirect Costs of Diabetes in the United States in 1992. Alexandria, VA: American Diabetes Association, pp. 1-27, 1993.|
|**From Rubin RJ, Altman WM, Mendelson DN: Health care expenditures for people with diabetes mellitus, 1992. J Clin Endocrinol Metab 78:809A-809F, 1994.|
$3,800 higher for people with diabetes than for people without diabetes ($6,425 versus $2,604).
The fact that 62 percent of direct health care costs among people with diabetes and 82 percent of costs directly attributable to diabetes are incurred in the hospital setting suggests that the majority of costs are associated with the treatment of the late, chronic complications of diabetes.
SCREENING FOR TYPE 2 DIABETES
One-third of diabetes in the United States is undiagnosed, and one-third to one-half of all diabetes worldwide is undiagnosed. This finding, combined with the fact that glycemic management can prevent or delay the development of complications, and the fact that diabetic patients may already have complications at clinical diagnosis, have lead some to call for public health screening for type 2 diabetes. In general, screening is appropriate in asymptomatic populations when six specific conditions are met (see Table 6).
|Characteristics of Diseases that Warrant Diabetes Screening|
|SOURCE: Engelgau, M. M.; Venkat Narayan, K. M.; and Herman, W. H. (2000). "Screening for Type 2 Diabetes." Diabetes Care 23:1563580.|
Diabetes imposes substantial morbidity and mortality on the population. The natural history of type 2 diabetes is well understood, and with systematic testing, diabetes can be diagnosed in asymptomatic, preclinical, subjects. Unfortunately, although it is clear that intensified management can improve outcomes, no studies have demonstrated the effectiveness or safety of early treatment. Likewise, there is no consensus as to the optimal approach to screening for type 2 diabetes. Ideally, a screening test should be both sensitive and specific. Generally, however, trade-offs must be made between sensitivity and specificity (increasing sensitivity reduces specificity, and increasing specificity reduces sensitivity). In some health systems, the costs of screening and treatment are reasonable, but in others they are simply unaffordable. Finally, although it is recognized that screening must be an ongoing process, no empirical data exist to indicate the optimal screening frequency.
Questionnaires that use self-reported demographic, behavioral, and past medical history to assign a person to a higher or lower risk group; fasting, random, and postprandial urine glucose tests; fasting, random, and postprandial capillary whole blood and capillary plasma glucose tests; fasting, random, and postprandial venous whole blood and plasma glucose tests; and hemoglobin A1c have all been evaluated as screening tests for diabetes. In general, questionnaires perform rather poorly as screening tests for diabetes. Measurement of glycosuria using a cut-off point greater than or equal to a trace value generally has a low sensitivity and a high specificity. Capillary or venous whole blood or plasma glucose determinations have generally performed better than urine glucose testing. With both urine and blood testing, random, postprandial, and glucose-loaded tests perform better than fasting tests. There is little consensus, however, as to optimal cut-points for defining positive tests. Screening with hemoglobin A1c has suffered from lack of standardization of the assay. Even as this problem has been addressed, the test has generally been found to be specific but less sensitive than glucose measurements.
Accordingly, the American Diabetes Association has recommended that clinicians should be vigilant and recognize clinical histories and signs suggestive of diabetes that warrant testing. Generally, screening of high-risk individuals for type 2 diabetes should be performed only as part of ongoing medical care, understanding that the evidence is incomplete and questions remain as to the benefits and risks of early treatment, the optimal screening methods and cut-points, and screening frequency. Community-based screening for diabetes is generally associated with a low yield and poor follow-up, and it probably does not represent a good use of resources.
WILLIAM H. HERMAN
LIZA L. ILAG
(SEE ALSO: Cardiovascular Diseases; Glycosylated Hemoglobin; Noncommunicable Disease Control; Nutrition; Screening)
Centers for Disease Control and Prevention (1997). Diabetes Surveillance, 1997. Atlanta, GA: CDC.
DCCT Research Group (1993). "The Effect of Intensive Treatment of Diabetes on the Development and Progression of Long-Term Complications in Insulin-Dependent Diabetes Mellitus." New England Journal of Medicine 329: 97786.
Engelgau, M. M.; Venkat Narayan, K. M.; and Herman, W. H. (2000). "Screening for Type 2 Diabetes." Diabetes Care 23:1563580.
Fox-Ray, N.; Mills, S.; and Thamer, M. (1993). Direct and Indirect Costs of Diabetes in the United States in 1992. Alexandria, VA: American Diabetes Association.
King, H.; Aubert, R. E.; and Herman, W. H. (1998). "Global Burden of Diabetes, 1995025: Prevalence, Numerical Estimates, and Projections." Diabetes Care 21:1414431.
Lebovitz, H. E., ed. (1998) Therapy for Diabetes Mellitus and Related Disorders, 3rd edition. Alexandria, VA: American Diabetes Association.
National Diabetes Data Group (1995). Diabetes in America, 2nd edition. Bethesda, MD: National Institute of Health.
Rubin, R. J.; Altman, W. M.; and Mendelson, D. N. (1994). "Health Care Expenditures for People with Diabetes Mellitus, 1992." Journal of Clinical Endocrinolical Metabolism 78:809a09f.
UK Prospective Diabetes Study (UKPDS) Group (1998). "Intensive Blood-Glucose Control with Sulphonylureas or Insulin Compared with Conventional Treatment and Risk of Complications in Patients with Type 2 Diabetes." Lancet 352:85753. (Published erratum appears in Lancet 354:602.