Resource:Â National Diabetes Information Clearinghouse (NDIC)
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Almost everyone knows someone who has diabetes. An estimated 20.8 million people in the United Statesâ€”7.0 percent of the populationâ€”have diabetes, a serious, lifelong condition. Of those, 14.6 million have been diagnosed, and 6.2 million have not yet been diagnosed. In 2005, about 1.5 million people aged 20 or older were diagnosed with diabetes. For additional statistics, see the National Diabetes Statistics fact sheet online at www.diabetes.niddk.nih.gov/dm/pubs/statistics or call the National Diabetes Information Clearinghouse at 1â€“800â€“860â€“8747 to request a copy.
What is diabetes?
Diabetes is a disorder of metabolismâ€”the way our bodies use digested food for growth and energy. Most of the food we eat is broken down into glucose, the form of sugar in the blood. Glucose is the main source of fuel for the body.
After digestion, glucose passes into the bloodstream, where it is used by cells for growth and energy. For glucose to get into cells, insulin must be present. Insulin is a hormone produced by the pancreas, a large gland behind the stomach.
When we eat, the pancreas automatically produces the right amount of insulin to move glucose from blood into our cells. In people with diabetes, however, the pancreas either produces little or no insulin, or the cells do not respond appropriately to the insulin that is produced. Glucose builds up in the blood, overflows into the urine, and passes out of the body in the urine. Thus, the body loses its main source of fuel even though the blood contains large amounts of glucose.[Top]
What are the types of diabetes?
The three main types of diabetes are
Type 1 Diabetes
Type 1 diabetes is an autoimmune disease. An autoimmune disease results when the bodyâ€™s system for fighting infection (the immune system) turns against a part of the body. In diabetes, the immune system attacks and destroys the insulin-producing beta cells in the pancreas. The pancreas then produces little or no insulin. A person who has type 1 diabetes must take insulin daily to live.
At present, scientists do not know exactly what causes the bodyâ€™s immune system to attack the beta cells, but they believe that autoimmune, genetic, and environmental factors, possibly viruses, are involved. Type 1 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 can appear at any age.
Symptoms of type 1 diabetes usually develop over a short period, although beta cell destruction can begin years earlier. Symptoms may include increased thirst and urination, constant hunger, weight loss, blurred vision, and extreme fatigue. If not diagnosed and treated with insulin, a person with type 1 diabetes can lapse into a life-threatening diabetic coma, also known as diabetic ketoacidosis.
Type 2 Diabetes
The most common form of diabetes is type 2 diabetes. About 90 to 95 percent of people with diabetes have type 2. This form of diabetes is most often associated with older age, obesity, family history of diabetes, previous history of gestational diabetes, physical inactivity, and certain ethnicities. About 80 percent of people with type 2 diabetes are overweight.
Type 2 diabetes is increasingly being diagnosed in children and adolescents. However, nationally representative data on prevalence of type 2 diabetes in youth are not available.
When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin, but for unknown reasons the body cannot use the insulin effectively, a condition called insulin resistance. After several years, insulin production decreases. The result is the same as for type 1 diabetesâ€”glucose builds up in the blood and the body cannot make efficient use of its main source of fuel.
The symptoms of type 2 diabetes develop gradually. Their onset is not as sudden as in type 1 diabetes. Symptoms may include fatigue, frequent urination, increased thirst and hunger, weight loss, blurred vision, and slow healing of wounds or sores. Some people have no symptoms.
Some women develop gestational diabetes late in pregnancy. Although this form of diabetes usually disappears after the birth of the baby, women who have had gestational diabetes have a 20 to 50 percent chance of developing type 2 diabetes within 5 to 10 years. Maintaining a reasonable body weight and being physically active may help prevent development of type 2 diabetes.
About 3 to 8 percent of pregnant women in the United States develop gestational diabetes. As with type 2 diabetes, gestational diabetes occurs more often in some ethnic groups and among women with a family history of diabetes. Gestational diabetes is caused by the hormones of pregnancy or a shortage of insulin. Women with gestational diabetes may not experience any symptoms.[Top]
How is diabetes diagnosed?
The fasting blood glucose test is the preferred test for diagnosing diabetes in children and nonpregnant adults. It is most reliable when done in the morning. However, a diagnosis of diabetes can be made based on any of the following test results, confirmed by retesting on a different day:
Gestational diabetes is diagnosed based on blood glucose levels measured during the OGTT. Glucose levels are normally lower during pregnancy, so the cutoff levels for diagnosis of diabetes in pregnancy are lower. Blood glucose levels are measured before a woman drinks a beverage containing glucose. Then levels are checked 1, 2, and 3 hours afterward. If a woman has two blood glucose levels meeting or exceeding any of the following numbers, she has gestational diabetes: a fasting blood glucose level of 95 mg/dL, a 1-hour level of 180 mg/dL, a 2-hour level of 155 mg/dL, or a 3-hour level of 140 mg/dL.[Top]
What is pre-diabetes?
People with pre-diabetes have blood glucose levels that are higher than normal but not high enough for a diagnosis of diabetes. This condition raises the risk of developing type 2 diabetes, heart disease, and stroke.
Pre-diabetes is also called impaired fasting glucose (IFG) or impaired glucose tolerance (IGT), depending on the test used to diagnose it. Some people have both IFG and IGT.
Pre-diabetes is becoming more common in the United States, according to new estimates provided by the U.S. Department of Health and Human Services. About 40 percent of U.S. adults ages 40 to 74â€”or 41 million peopleâ€”had pre-diabetes in 2000. New data suggest that at least 54 million U.S. adults had pre-diabetes in 2002. Many people with pre-diabetes go on to develop type 2 diabetes within 10 years.
The good news is that if you have pre-diabetes, you can do a lot to prevent or delay diabetes. Studies have clearly shown that you can lower your risk of developing diabetes by losing 5 to 7 percent of your body weight through diet and increased physical activity. A major study of more than 3,000 people with IGT, a form of pre-diabetes, found that diet and exercise resulting in a 5 to 7 percent weight lossâ€”about 10 to 14 pounds in a person who weighs 200 poundsâ€”lowered the incidence of type 2 diabetes by nearly 60 percent. Study participants lost weight by cutting fat and calories in their diet and by exercising (most chose walking) at least 30 minutes a day, 5 days a week.[Top]
What are the scope and impact of diabetes?
Diabetes is widely recognized as one of the leading causes of death and disability in the United States. In 2002, it was the sixth leading cause of death. However, diabetes is likely to be underreported as the underlying cause of death on death certificates. About 65 percent of deaths among those with diabetes are attributed to heart disease and stroke.
Diabetes is associated with long-term complications that affect almost every part of the body. The disease often leads to blindness, heart and blood vessel 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.
In 2002, diabetes cost the United States $132 billion. Indirect costs, including disability payments, time lost from work, and premature death, totaled $40 billion; direct medical costs for diabetes care, including hospitalizations, medical care, and treatment supplies, totaled $92 billion.[Top]
Who gets diabetes?
Diabetes is not contagious. People cannot â€ścatchâ€ť it from each other. However, certain factors can increase the risk of developing diabetes.
Type 1 diabetes occurs equally among males and females but is more common in whites than in non-whites. Data from the World Health Organizationâ€™s Multinational Project for Childhood Diabetes indicate that type 1 diabetes is rare in most African, American Indian, and Asian populations. However, some northern European countries, including Finland and Sweden, have high rates of type 1 diabetes. The reasons for these differences are unknown. Type 1 diabetes develops most often in children but can occur at any age.
Type 2 diabetes is more common in older people, especially in people who are overweight, and occurs more often in African Americans, American Indians, some Asian Americans, Native Hawaiians and other Pacific Islander Americans, and Hispanics/Latinos. On average, non-Hispanic African Americans are 1.8 times as likely to have diabetes as non-Hispanic whites of the same age. Mexican Americans are 1.7 times as likely to have diabetes as non-Hispanic whites of similar age. (Data are not available for estimation of diabetes rates in other Hispanic/Latino groups.) American Indians have one of the highest rates of diabetes in the world. On average, American Indians and Alaska Natives are 2.2 times as likely to have diabetes as non-Hispanic whites of similar age. Although prevalence data for diabetes among Asian Americans and Pacific Islanders are limited, some groups, such as Native Hawaiians, Asians, and other Pacific Islanders residing in Hawaii (aged 20 or older) are more than twice as likely to have diabetes as white residents of Hawaii of similar age.
Diabetes prevalence in the United States is likely to increase for several reasons. First, a large segment of the population is aging. Also, Hispanics/Latinos and other minority groups at increased risk make up the fastest-growing segment of the U.S. population. Finally, Americans are increasingly overweight and sedentary. According to recent estimates from the Centers for Disease Control and Prevention (CDC), diabetes will affect one in three people born in 2000 in the United States. The CDC also projects the prevalence of diagnosed diabetes in the United States will increase 165 percent by 2050.Top]
How is diabetes managed?
Before the discovery of insulin in 1921, everyone with type 1 diabetes died within a few years after diagnosis. Although insulin is not considered a cure, its discovery was the first major breakthrough in diabetes treatment.
Today, healthy eating, physical activity, and taking insulin are the basic therapies for type 1 diabetes. The amount of insulin must be balanced with food intake and daily activities. Blood glucose levels must be closely monitored through frequent blood glucose checking. People with diabetes also monitor blood glucose levels several times a year with a laboratory test called the A1C. Results of the A1C test reflect average blood glucose over a 2- to 3-month period.
Healthy eating, physical activity, and blood glucose testing are the basic management tools for type 2 diabetes. In addition, many people with type 2 diabetes require oral medication, insulin, or both to control their blood glucose levels.
Adults with diabetes are at high risk for cardiovascular disease (CVD). In fact, at least 65 percent of those with diabetes die from heart disease or stroke. Managing diabetes is more than keeping blood glucose levels under controlâ€”it is also important to manage blood pressure and cholesterol levels through healthy eating, physical activity, and use of medications (if needed). By doing so, those with diabetes can lower their risk. Aspirin therapy, if recommended by the health care team, and smoking cessation can also help lower risk.
People with diabetes must take responsibility for their day-to-day care. Much of the daily care involves keeping blood glucose levels from going too low or too high. When blood glucose levels drop too lowâ€”a condition known as hypoglycemiaâ€”a person can become nervous, shaky, and confused. Judgment can be impaired, and if blood glucose falls too low, fainting can occur.
A person can also become ill if blood glucose levels rise too high, a condition known as hyperglycemia.
People with diabetes should see a health care provider who will help them learn to manage their diabetes and who will monitor their diabetes control. Most people with diabetes get care from primary care physiciansâ€”internists, family practice doctors, or pediatricians. Often, having a team of providers can improve diabetes care. A team can include
and other health care providers, such as cardiologists and other specialists. In addition, the team for a pregnant woman with type 1, type 2, or gestational diabetes should include an obstetrician who specializes in caring for women with diabetes. The team can also include a pediatrician or a neonatologist with experience taking care of babies born to women with diabetes.
The goal of diabetes management is to keep levels of blood glucose, blood pressure, and cholesterol as close to the normal range as safely possible. A major study, the Diabetes Control and Complications Trial (DCCT), sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), showed that keeping blood glucose levels close to normal reduces the risk of developing major complications of type 1 diabetes.
This 10-year study, completed in 1993, included 1,441 people with type 1 diabetes. The study compared the effect of two treatment approachesâ€”intensive management and standard managementâ€”on the development and progression of eye, kidney, nerve, and cardiovascular complications of diabetes. Intensive treatment aimed to keep A1C levels as close to normal (6 percent) as possible. Researchers found that study participants who maintained lower levels of blood glucose through intensive management had significantly lower rates of these complications. More recently, a follow-up study of DCCT participants showed that the ability of intensive control to lower the complications of diabetes has persisted more than 10 years after the trial ended.
The United Kingdom Prospective Diabetes Study, a European study completed in 1998, showed that intensive control of blood glucose and blood pressure reduced the risk of blindness, kidney disease, stroke, and heart attack in people with type 2 diabetes.[Top]
Hope through Research
NIDDK conducts research in its own laboratories and supports a great deal of basic and clinical research in medical centers and hospitals throughout the United States. It also gathers and analyzes statistics about diabetes. Other Institutes at the National Institutes of Health (NIH) conduct and support research on diabetes-related eye diseases, heart and vascular complications, autoimmunity, pregnancy, and dental problems.
Other Government agencies that sponsor diabetes programs are the CDC, the Indian Health Service, the Health Resources and Services Administration, the Department of Veterans Affairs, and the Department of Defense.
Many organizations outside the Government support diabetes research and education activities. These organizations include the American Diabetes Association (ADA), the Juvenile Diabetes Research Foundation International (JDRF), and the American Association of Diabetes Educators.
In recent years, advances in diabetes research have led to better ways of managing diabetes and treating its complications. Major advances include
What will the future bring?
Researchers continue to look for the cause or causes of diabetes and ways to manage, prevent, or cure the disorder. Scientists are searching for genes that may be involved in type 1 or type 2 diabetes. Some genetic markers for type 1 diabetes have been identified, and it is now possible to screen relatives of people with type 1 diabetes to determine whether they are at risk.
Type 1 Diabetes
A number of Federally-funded research studies and clinical trials are under way. Studies focus on the prevention and causes of type 1 diabetes as well as experimental treatments such as islet transplantation.
The Environmental Determinants of Diabetes in the Young Consortium
TEDDY is funded by the NIDDK, the National Institute of Allergy and Infectious Diseases (NIAID), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the National Institute of Environmental Health Sciences, the CDC, the JDRF, and the ADA. For more information, see www.niddk.nih.gov/patient/TEDDY/TEDDY.htm.
Type 1 Diabetes TrialNet
TrialNet studies are focusing on
For more information, see www.DiabetesTrialNet.org or call 1â€“800â€“HALTâ€“DM1 (1â€“800â€“425â€“8361).
In many ways, the TrialNet studies build on the advances and insights gained from earlier research in type 1 diabetes. For example, researchers learned a great deal about how to predict type 1 diabetes in at-risk people from the Diabetes Prevention Trialâ€”Type 1 (DPTâ€“1). This study showed that people at risk of developing type 1 diabetes can be identified. The DPT-1 researchers discovered ways to identify two populations at risk of developing type 1 diabetes within 5 years: those at high risk (with at least a 50 percent chance) and those with an intermediate risk (having a 25 to 50 percent risk). Then researchers explored possible ways of preventing type 1 diabetes in both groups. TrialNet will identify people at risk who may be eligible for clinical trials. In addition, TrialNet will conduct trials to save beta cell function in those with new onset type 1 diabetes.
TrialNet is funded by the NIDDK, NICHD, and NIAID. JDRF and ADA also support this effort.
The Immune Tolerance Network
Scientists have made many advances in islet transplantation in recent years. Since reporting their findings in the June 2000 issue of the New England Journal of Medicine, researchers at the University of Alberta in Edmonton, Alberta, Canada, have continued to use a procedure called the Edmonton protocol to transplant pancreatic islets into people with type 1 diabetes. Before use of the Edmonton protocol, during the 1990s, less than 10 percent of islet cell transplant recipients were able to control blood glucose levels for more than 1 year without insulin injections.
The Collaborative Islet Transplant Registry (CITR), funded by NIDDK, was created in 2001. CITRâ€™s mission is to expedite progress and promote safety in islet transplantation by collecting, analyzing, and communicating data on islet transplantation. The CITR will study islet transplantation alone as well as islet transplantation following kidney transplant.
The September 2005 CITR annual report noted that with use of the Edmonton protocol, after 1 year, 58 percent of those who had transplants no longer needed to inject insulin. Of those who were still insulin-dependent 1 year after transplantation (33 percent of those followed by the registry), requirements for insulin were decreased. The average reduction in insulin requirements was 69 percent. In summary, a total of 91 percent of those with transplants showed improvement following transplantation. The success of the Edmonton protocol has been confirmed at other study sites, including the NIDDK.
The goal of islet transplantation is to infuse enough islets to control the blood glucose level without insulin injections. For an average-sized person (154 pounds), a typical transplant requires about 1 million islets, extracted from two donor pancreases. Because good control of blood glucose can slow or prevent the progression of complications associated with diabetes, such as nerve or eye damage, a successful transplant may reduce the risk of these complications. However, transplanted islets lose their ability to function over time. Also, a transplant recipient needs to take immunosuppressive drugs to stop the immune system from rejecting the transplanted islets.
These drugs have significant side effects, and their long-term effects are still unknown. Immediate side effects of immunosuppressive drugs may include mouth sores and gastrointestinal problems, such as stomach upset or diarrhea. Patients may also have increased blood cholesterol levels, decreased white blood cell counts, decreased kidney function, and increased susceptibility to bacterial and viral infections. Taking immunosuppressive drugs increases the risk of tumors and cancer as well. Researchers are trying to find safer or less toxic immunosuppressants or new approaches that will allow successful transplantation without the use of immunosuppressive drugs.
The results of the Edmonton protocol are very encouraging, but more research is needed to develop safer and more effective immunosuppression and to enhance islet survival after transplantation.
Another obstacle to widespread use of islet transplantation is the severe shortage of islets. Only about 6,000 pancreases a year become available for transplantation or for harvesting of islets. However, researchers are pursuing alternative sources, such as creating islets from other types of cells. New technologies could then be employed to grow islets in the laboratory.
Type 2 Diabetes
Diabetes Prevention Program
The findings of the DPP, released in August 2001, showed that people at high risk for type 2 diabetes could sharply lower their chances of developing the disorder through diet and exercise. In addition, treatment with the oral diabetes drug metformin also reduced diabetes risk, though less dramatically. Metformin lowers the amount of glucose released by the liver and also fights insulin resistance, a condition in which the body doesn't use insulin properly.
Participants randomly assigned to intensive lifestyle intervention reduced their risk of getting type 2 diabetes by almost 60 percent. On average, this group maintained their physical activity at 30 minutes per day, usually with walking or other moderate intensity exercise, and lost 5 to 7 percent of their body weight. Participants randomized to treatment with metformin reduced their risk of getting type 2 diabetes by 31 percent.
Of the 3,234 participants enrolled in the DPP, 45 percent were from minority groups that suffer disproportionately from type 2 diabetes: African Americans, Hispanics/Latinos, Asian Americans and Pacific Islanders, and American Indians. The trial also recruited other groups known to be at higher risk for type 2 diabetes, including individuals aged 60 and older, women with a history of gestational diabetes, and people with a first-degree relative with type 2 diabetes. Participants are being followed to check for long-term effects of the interventions, including the effects on risk of CVD.
Type 2 Diabetes in Children and Teens
The main goal of the study is to determine how well each type of treatment controls blood glucose levels. The study also will evaluate how long each type of treatment is effective.
The STOPP-T2D (Studies to Treat or Prevent Pediatric Type 2 Diabetes) study, sponsored by NIDDK with support from the ADA, is exploring methods to lower risk factors for type 2 diabetes and CVD in middle-school children (grades 6 through 8) at eight sites. A 3-year program will focus on the benefits of improving nutrition, promoting physical activity, and making changes in behavior.
Preventing and Treating CVD in People with Type 2 Diabetes
The Look AHEAD (Action for Health in Diabetes) trial is the largest clinical trial to date to examine the long-term health effects of voluntary weight loss. This multi-center, randomized clinical trial is studying the effects of a lifestyle intervention designed to achieve and maintain weight loss over the long term through decreased caloric intake and increased exercise. Look AHEAD will focus on the disorder most associated with being overweight or obese, type 2 diabetes, and on the outcome that causes the greatest morbidity and mortality in people with type 2 diabetes, CVD.
The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, a multi-center, randomized trial, is studying three approaches to preventing major cardiovascular events in individuals with type 2 diabetes. ACCORD is designed to compare current practice guidelines with more intensive glycemic control in 10,000 individuals with type 2 diabetes, including those at especially high risk for CVD events because of age, evidence of subclinical atherosclerosis, or existing clinical CVD. More intensive control of blood pressure than is called for in current guidelines and a medication to reduce triglyceride levels and raise HDL (good) cholesterol levels will also be studied in subgroups of these 10,000 volunteers. Each treatment strategy will be accompanied by standard advice regarding lifestyle choices, including diet, physical activity, and smoking cessation, appropriate for individuals with diabetes.
The primary outcome to be measured is the first occurrence of a major CVD event, specifically heart attack, stroke, or cardiovascular death. In addition, the study will investigate the impact of the treatment strategies on other cardiovascular outcomes; total mortality; limb amputation; eye, kidney, or nerve disease; health-related quality of life; and cost-effectiveness.
The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial, a 5-year, multi-center clinical trial, is comparing medical versus early surgical management of patients with type 2 diabetes who also have coronary artery disease and stable angina or ischemia. At the same time, BARI 2D will study the effect of two different strategies to control blood glucoseâ€”providing insulin versus increasing the sensitivity of the body to insulinâ€”on the risk of cardiovascular mortality and morbidity.
A complete listing of clinical trials can be found at www.ClinicalTrials.gov.[Top]
Points to Remember
What is diabetes?
What are the main types of diabetes?
What are the impacts of diabetes?
Who gets diabetes?
For More Information
To learn more about type 1, type 2, and gestational diabetes, as well as diabetes research, statistics, and education, contact:
National Diabetes Education Program
To find a clinical trial, check NIHâ€™s database at www.ClinicalTrials.gov online.
To participate in studies about type 1 diabetes, contact:
Type 1 Diabetes TrialNet
The following organizations also distribute materials and support programs for people with diabetes and their families and friends:
American Diabetes Association
Juvenile Diabetes Research Foundation International
National Diabetes Information Clearinghouse
The National Diabetes Information Clearinghouse (NDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Human Services. Established in 1978, the Clearinghouse provides information about diabetes to people with diabetes and to their families, health care professionals, and the public. The NDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about diabetes.
Publications produced by the Clearinghouse are carefully reviewed by both NIDDK scientists and outside experts.
This publication is not copyrighted. The Clearinghouse encourages users of this publication to duplicate and distribute as many copies as desired.
NIH Publication No. 06â€“3873
National Diabetes Information Clearinghouse (2008). Diabetes overview. Retrieved November 4, 2008, from http://diabetes.niddk.nih.gov/dm/pubs/overview/index.htm#what