What is
Diabetes?
Questions and Answers about
diabetes.
Almost everyone knows someone who has diabetes. An
estimated 20.8 million people in the United States—7.0
percent of the population—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 1–800–860–8747 to request a copy.
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What is diabetes?
Diabetes is a metabolism disorder, 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.
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What are the types of diabetes?
The three main types of diabetes are
- type 1 diabetes
- type 2 diabetes
- gestational diabetes
Type 1 Diabetes
Type 1 diabetes is an autoimmune disease. An autoimmune
disease results when the body's system for fighting
infection (the immune system) turns against a part
of the body. In diabetes, the immune system attacks
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 body'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 diabetes—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.
Gestational Diabetes
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.
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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:
- A blood glucose level of 126 milligrams per deciliter
(mg/dL) or more after an 8-hour fast. This test
is called the fasting blood glucose test.
- A blood glucose level of 200 mg/dL or more 2 hours
after drinking a beverage containing 75 grams of
glucose dissolved in water. This test is called the
oral glucose tolerance test (OGTT).
- A random (taken at any time of day) blood glucose
level of 200 mg/dL or more, along with the presence
of diabetes symptoms.
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.
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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.
- IFG is a condition in which the blood glucose
level is high (100 to 125 mg/dL) after an overnight
fast, but is not high enough to be classified as
diabetes. (The former definition of IFG was 110
mg/dL to 125 mg/dL.)
- IGT is a condition in which the blood glucose level
is high (140 to 199 mg/dL) after a 2-hour oral glucose
tolerance test, but is not high enough to be classified
as diabetes.
Pre-diabetes is far more common in the United States
than previously believed, 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
74, or 41 million people, currently have the condition.
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 loss, about 10
to 14 pounds in a person who weighs 200 pounds, 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.
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What is
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.
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Who gets diabetes?
Diabetes is not contagious. People cannot “catch” 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 Organization'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 is 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.
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Could you have diabetes and
not know it?
There are 20.8 million children and adults in the
US with diabetes -- and nearly one-third of them
(or 6.2 million people) do not know it! Take the
American Diabetes Association's Diabetes
Risk Test to see if
you are at risk for having or developing type two
diabetes. Diabetes is more common in African Americans,
Latinos, Native Americans, Asian Americans and Pacific
Islanders. If you are a member of one of these ethnic
groups, you need to pay special attention to this
test.
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