What Is Diabetes? Diabetes is a disorder
of metabolism--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 is supposed to
automatically produce 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. 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 the insulin-producing beta cells
in the pancreas and destroys them. The
pancreas then produces little or no
insulin. Someone with type 1 diabetes
needs to 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.
Type 1 diabetes develops most often in
children and young adults, but the
disorder 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 include increased thirst and
urination, constant hunger, weight loss,
blurred vision, and extreme fatigue. If
not diagnosed and treated with insulin, a
person 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 usually develops in adults age 40
and older and is most common in adults
over age 55. About 80 percent of people
with type 2 diabetes are overweight. Type
2 diabetes is often part of a metabolic
syndrome that includes obesity, elevated
blood pressure, and high levels of blood
lipids. Unfortunately, as more children
and adolescents become overweight, type 2
diabetes is becoming more common in young
people.
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. They are not as sudden in onset
as in type 1 diabetes. Some people have no
symptoms. Symptoms may include fatigue or
nausea, frequent urination, unusual
thirst, weight loss, blurred vision,
frequent infections, and slow healing of
wounds or sores.
Gestational Diabetes
Gestational diabetes develops only during
pregnancy. Like type 2 diabetes, it occurs
more often in African Americans, American
Indians, Hispanic Americans, and people
with a family history of diabetes. Though
it usually disappears after delivery, the
mother is at increased risk of getting
type 2 diabetes later in life.
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What Tests Are Recommended for Diagnosing
Diabetes? The fasting plasma glucose test
is the preferred test for diagnosing type
1 or type 2 diabetes. However, a diagnosis
of diabetes is made for any one of three
positive tests, with a second positive
test on a different day:
A random plasma glucose value (taken any
time of day) of 200 mg/dL or more, along
with the presence of diabetes symptoms.
A plasma glucose value of 126 mg/dL or
more, after a person has fasted for 8
hours.
An oral glucose tolerance test (OGTT)
plasma glucose value of 200 mg/dL or more
in the blood sample, taken 2 hours after a
person has consumed a drink containing 75
grams of glucose dissolved in water. This
test, taken in a laboratory or the
doctor's office, measures plasma glucose
at timed intervals over a 3-hour period.
Gestational diabetes is diagnosed based on
plasma glucose values measured during the
OGTT. Glucose levels are normally lower
during pregnancy, so the threshold values
for diagnosis of diabetes in pregnancy are
lower. If a woman has two plasma glucose
values meeting or exceeding any of the
following numbers, she has gestational
diabetes: a fasting plasma 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 Are the Other Forms of Impaired
Glucose Metabolism, Also Called
Prediabetes? People with prediabetes, a
state between "normal" and "diabetes," are
at risk for developing diabetes, heart
attacks, and strokes. About 16 million
people ages 40 to 74 in the United States
have prediabetes. There are two forms of
prediabetes.
Impaired Fasting Glucose
A person has impaired fasting glucose
(IFG) when fasting plasma glucose is 110
to 125 mg/dL. This level is higher than
normal but less than the level indicating
a diagnosis of diabetes.
Impaired Glucose Tolerance
Impaired glucose tolerance (IGT) means
that blood glucose during the oral glucose
tolerance test is higher than normal but
not high enough for a diagnosis of
diabetes. IGT is diagnosed when the
glucose level is 141 to 199 mg/dL 2 hours
after a person is given a drink containing
75 grams of glucose.
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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 1999, about
450,000 deaths occurred among adults with
diabetes.
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, strokes, 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 $40.2
billion; direct medical costs for diabetes
care, including hospitalizations, medical
care, and treatment supplies, totaled
$91.8 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 nonwhites. 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 not known.
Type 2 diabetes is more common in older
people, especially in people who are
overweight, and occurs more often in
African Americans, American Indians, Asian
and Pacific Islander Americans, and
Hispanic Americans. On average,
non-Hispanic African Americans are twice
as likely to have diabetes as non-Hispanic
whites of the same age. Hispanic Americans
are nearly twice as likely to have
diabetes as non-Hispanic whites. American
Indians have the highest rates of diabetes
in the world. Among the Pima Indians
living in Arizona, for example, half of
all adults have type 2 diabetes. On
average, American Indians and Alaska
Natives are 2.6 times as likely to have
diabetes as non-Hispanic whites. Although
prevalence data for diabetes among Asian
Americans and Pacific Islanders is
limited, some groups, such as Native
Hawaiians, are 2.5 times more likely to
have diabetes as white residents of
Hawaii.
The prevalence of diabetes in the United
States is likely to increase for several
reasons. First, a large segment of the
population is aging. Also, Hispanic
Americans and other minority groups make
up the fastest-growing segment of the U.S.
population. Finally, Americans are
increasingly overweight and sedentary.
According to recent estimates, the
prevalence of diabetes in the United
States is predicted to be 8.9 percent of
the population by 2025.
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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 insulin via injection or an insulin
pump 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.
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 and insulin to
control their blood glucose levels.
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 low from certain diabetes medicines--a
condition known as hypoglycemia--a person
can become nervous, shaky, and confused.
Judgment can be impaired. If blood glucose
falls too low, a person can faint.
A person can also become ill if blood
glucose levels rise too high, a condition
known as hyperglycemia.
People with diabetes should see a doctor
who helps them learn to manage their
diabetes and monitors their diabetes
control. An endocrinologist is one type of
doctor who may specialize in diabetes
care. In addition, people with diabetes
often see ophthalmologists for eye
examinations, podiatrists for routine foot
care, and dietitians and diabetes
educators to help teach the skills of
day-to-day diabetes management.
The goal of diabetes management is to keep
blood glucose levels 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
as close to normal as safely possible
reduces the risk of developing major
complications of type 1 diabetes.
The 10-year study, completed in 1993,
included 1,441 people with type 1
diabetes. The study compared the effect of
two treatment approaches--intensive
management and standard management--on the
development and progression of eye,
kidney, and nerve complications of
diabetes. Intensive treatment aimed at
keeping hemoglobin A-1-c as close to
normal (6 percent) as possible. Hemoglobin
A-1-c reflects average blood sugar over a
2- to 3-month period. 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 followup study of DCCT
participants showed that the ability of
intensive control to lower the
complications of diabetes persists up to 4
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.
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What Is the Status of Diabetes 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, pregnancy, and
dental problems.
Other Government agencies that sponsor
diabetes programs are the Centers for
Disease Control and Prevention, the Indian
Health Service, the Health Resources and
Services Administration, the Department of
Veterans Affairs, and the Department of
Defense.
Many organizations outside of the
Government support diabetes research and
education activities. These organizations
include the American Diabetes Association,
the Juvenile Diabetes Research Foundation
International, and the American
Association of Diabetes Educators.
In recent years, advances in diabetes
research have led to better ways to manage
diabetes and treat its complications.
Major advances include
The development of a quick-acting insulin
analog.
Better ways to monitor blood glucose and
for people with diabetes to check their
own blood glucose levels.
Development of external insulin pumps that
deliver insulin, replacing daily
injections.
Laser treatment for diabetic eye disease,
reducing the risk of blindness.
Successful transplantation of kidneys and
pancreas in people whose own kidneys fail
because of diabetes.
Better ways of managing diabetes in
pregnant women, improving chances of
successful outcomes.
New drugs to treat type 2 diabetes and
better ways to manage this form of
diabetes through weight control.
Evidence that intensive management of
blood glucose reduces and may prevent
development of diabetes complications.
Demonstration that antihypertensive drugs
called ACE (angiotensin-converting enzyme)
inhibitors prevent or delay kidney failure
in people with diabetes.
Promising results with islet
transplantation for type 1 diabetes
reported by the University of Alberta in
Canada. A nationwide clinical trial funded
by the NIH and the Juvenile Diabetes
Research Foundation International is
currently trying to replicate the Canadian
advance.
Evidence that people at high risk for type
2 diabetes can lower their chances of
developing the disease through diet and
exercise.
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What Will the Future Bring? In the future,
it may be possible to administer insulin
through inhalers, a pill, or a patch.
Devices are also being developed that can
monitor blood glucose levels without
having to prick a finger to get a blood
sample.
Researchers continue to search for the
cause or causes of diabetes and ways to
prevent and cure the disorder. Scientists
are looking 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 see if they are at risk.
The Diabetes Prevention Trial--Type 1
(DPT-1) identifies relatives at risk for
developing type 1 diabetes and treats them
with an oral form of insulin in the hope
of preventing type 1 diabetes. In the same
study, researchers recently completed a
separate trial in which they found that
low-dose insulin injections do not prevent
type 1 diabetes in relatives of people
with type 1 diabetes. For more
information, call 1-800-HALT-DM1
(1-800-425-8361) or see
www.niddk.nih.gov/patient/
dpt_1/dpt_1.htm on the Internet.
The DPT-1 is funded by the NIDDK, the
National Institute of Allergy and
Infectious Diseases, the National
Institute of Child Health and Human
Development, and the National Center for
Research Resources within the National
Institutes of Health as well as the
American Diabetes Association and the
Juvenile Diabetes Research Foundation
International.
Transplantation of the pancreas or
insulin-producing beta cells offers the
best hope of cure for people with type 1
diabetes. Some pancreas transplants have
been successful. However, people who have
transplants must take powerful drugs to
prevent rejection of the transplanted
organ. These drugs are costly and may
eventually cause other health problems.
Scientists are working to develop less
harmful drugs and better methods of
transplanting beta cells to prevent
rejection by the body. Using techniques of
bioengineering, researchers are also
trying to create artificial beta cells
that secrete insulin in response to
increased glucose levels in the blood.
Recently, researchers at the University of
Alberta in Edmonton, Canada, announced
promising results with islet
transplantation in seven patients with
type 1 diabetes. At the time of the report
in the New England Journal of Medicine,
all seven patients who had received the
transplant remained free of insulin
injections up to 14 months after the
procedure.
A clinical trial funded by the NIH and the
Juvenile Diabetes Research Foundation
International will try to replicate the
Edmonton advance. With the insights gained
from this trial and other studies,
scientists hope to further refine methods
of islet harvesting and transplantation
and learn more about the immune processes
that affect rejection and acceptance of
transplanted islets.
In 1996, NIDDK launched its Diabetes
Prevention Program (DPP). The goal of this
research effort was to learn how to
prevent or delay type 2 diabetes in people
with impaired glucose tolerance (IGT), a
strong risk factor for type 2 diabetes.
The findings of the DPP, which were
released in August 2001, showed that
people at high risk for type 2 diabetes
could sharply lower their chances of
developing the disease through diet and
exercise. In addition, treatment with the
oral diabetes drug metformin also reduced
diabetes risk, though less dramatically.
Participants randomly assigned to
intensive lifestyle intervention reduced
their risk of getting type 2 diabetes by
58 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, Hispanic
Americans, 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 age 60 and older, women with a
history of gestational diabetes, and
people with a first-degree relative with
type 2 diabetes.
Several new drugs have been developed to
treat type 2 diabetes. By using the oral
diabetes medications now available, many
people can control blood glucose levels
without insulin injections. Studies are
under way to determine how best to use
these drugs to manage type 2 diabetes.
Scientists also are investigating
strategies for weight loss in people with
type 2 diabetes.
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Points to Remember What is diabetes?
a disorder of metabolism--the way the body
digests food for energy and growth
What are the main types of diabetes?
type 1 diabetes
type 2 diabetes
gestational diabetes
What is the impact of diabetes?
affects 17 million people
is a leading cause of death and disability
costs $132 billion per year
Who gets diabetes?
people of any age
people with a family history of diabetes
most common in older people, overweight
and sedentary people, African Americans,
Alaska Natives, American Indians, Asian
and Pacific Islander Americans, and
Hispanic Americans
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Where Is More Information Available? For
more information about type 1, type 2, and
gestational diabetes, as well as diabetes
research, statistics, and education,
contact
National Diabetes Information
Clearinghouse
1 Information Way
Bethesda, MD 20892-3560
Phone: 1-800-860-8747 or (301) 654-3327
Email:
ndic
@info.niddk.nih.gov
The following organizations also
distribute materials and support programs
for people with diabetes and their
families and friends:
American Diabetes Association
National Service Center
1701 North Beauregard Street
Alexandria, VA 22311
Phone: 1-800-342-2383 or (703) 549-1500
Internet:
www.diabetes.org
Juvenile Diabetes Research Foundation
International
120 Wall Street, 19th Floor
New York, NY 10005
Phone: 1-800-533-2873 or (212) 785-9500
Internet:
www.jdrf.org
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National Diabetes Information
Clearinghouse
1 Information Way
Bethesda, MD 20892-3560
Email:
ndic
@info.niddk.nih.gov
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 under 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. 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.
