Almost
everyone knows someone who has diabetes.
An estimated 18.2 million people--6.3 percent of the population--in
the United States have diabetes--a serious, lifelong condition.
Of those, 13 million have been diagnosed. About 5.2 million
people have not yet been diagnosed. Each year, about 1.3 million
people age 20 or older are diagnosed with diabetes.
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.
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 is associated with
older age, obesity, family history of diabetes, previous history
of gestational diabetes, physical inactivity, and ethnicity.
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. 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 among women with a family history
of diabetes. Women who have had gestational diabetes have
a 20 to 50 percent chance of developing type 2 diabetes within
5 to 10 years.
What
tests are recommended for diagnosing diabetes?
The fasting
plasma glucose test is the preferred test for diagnosing type
1 or type 2 diabetes and is most reliable
when done in the morning. 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.
What
are the other forms of impaired glucose metabolism, also called
pre-diabetes?
People
with pre-diabetes, a state between "normal" and
"diabetes," are at risk for developing
diabetes, heart attacks, and strokes. However, studies suggest
that weight loss and increased physical activity can prevent
or delay diabetes. There are two forms of pre-diabetes.
Impaired
Fasting Glucose
A person
has impaired fasting glucose (IFG) when fasting plasma glucose
is 100 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 140 to 199 mg/dL 2 hours after a person is
given a drink containing 75 grams of glucose.
In a cross-section
of American adults age 40 to 74, tested during the period
1988 to 1994, 20.1 million (21.1 percent) had pre-diabetes.
Of those, 9.6 million (10.1 percent) had IFG and 14.2 million
(14.9 percent) had IGT.
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 2000, 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, 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 billion; direct medical costs for diabetes
care, including hospitalizations, medical care, and treatment
supplies, totaled $92 billion.
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, some Asian Americans, Native Hawaiians and
other Pacific Islander Americans, and Hispanic Americans.
On average, non-Hispanic African Americans are 1.6 times as
likely to have diabetes as non-Hispanic whites of the same
age. Hispanic Americans are 1.5 times as likely to have diabetes
as non-Hispanic whites of similar age. American Indians have
one of the highest rates of diabetes in the world. On average,
American Indians and Alaska Natives are 2.3 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
and Japanese and Filipino residents of Hawaii age 20 or older,
are about twice as likely to have diabetes as white residents
of Hawaii of similar age.
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.
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, insulin, or both 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--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 health care
provider 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 aims to keep hemoglobin A1C as close to normal (6
percent) as possible. Hemoglobin A1C 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 has persisted 8 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.
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, 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 quick-acting and long-acting insulin analogues
- better
ways to monitor blood glucose and for people with diabetes
to check their own blood glucose levels
- research
advances in noninvasive blood glucose monitoring
- 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 two types of antihypertensive drugs, ACE (angiotensin-converting
enzyme) inhibitors and ARBs (angiotensin receptor blockers),
are more effective in reducing a decline in kidney function
than other antihypertensive drugs in people with diabetes
- promising
results with islet transplantation for type 1 diabetes reported
by the University of Alberta in Canada
- evidence
that people at high risk for type 2 diabetes can lower their
chances of developing the disease through diet, weight loss,
and physical activity
What
will the future bring?
Prevention
of Diabetes
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.
Type
1 Diabetes
The Diabetes
Prevention Trial--Type 1 (DPT-1) identified relatives at risk
for developing type 1 diabetes and investigated two ways to
delay or prevent type 1 diabetes. Neither low-dose insulin
injections nor an oral form of insulin were successful in
delaying or preventing type 1 diabetes in people at risk.
The DPT-1
was 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.
Researchers
are working on a way to help people with type 1 diabetes live
without daily injections of insulin. In an experimental procedure
called islet transplantation, islets are taken from a donor
pancreas and transferred into another person. Once implanted,
the beta cells in these islets begin to make and release insulin.
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, Canada, have continued
to use a procedure called the Edmonton protocol to transplant
pancreatic islets into people with type 1 diabetes. A multicenter
clinical trial of the Edmonton protocol for islet transplantation
is currently under way, and results will be announced in several
years. According to the International Islet Transplant Registry,
as of June 2003, about 50 percent of the patients have remained
insulin-free for up to 1 year after receiving a transplant.
A clinical trial of the Edmonton protocol is also being conducted
by the Immune Tolerance Network, funded by the National Institutes
of Health and the Juvenile Diabetes Research Foundation International.
The goal
of islet transplantation is to infuse enough islets to control
the blood glucose level without insulin injections. For an
average-sized person (70 kg), 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. But a transplant recipient
will need to take immunosuppressive drugs that stop the immune
system from rejecting the transplanted islets.
Researchers
are trying to find new approaches that will allow successful
transplantation without the use of immunosuppressive drugs,
thus eliminating the side effects that may accompany their
long-term use. These drugs have significant side effects and
their long-term effects are still not known. 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
do not fully know what long-term effects this procedure may
have. Also, although the early results of the Edmonton protocol
are very encouraging, more research is needed to answer questions
about how long the islets will survive and how often the transplantation
procedure will be successful.
A major
obstacle to widespread use of islet transplantation will be
the shortage of islet cells. The supply available from deceased
donors will be enough for only a small percentage of those
with type 1 diabetes. However, researchers are pursuing avenues
for alternative sources, such as creating islet cells from
other types of cells. New technologies could then be employed
to grow islet cells in the laboratory.
Type
2 Diabetes
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.
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?
- It
affects 18.2 million people--6.3 percent of the population.
- It
is a leading cause of death and disability.
- It
costs $132 billion per year.
Who gets
diabetes?
- people
of any age
- those
with a family history of diabetes
- most
common in older people, overweight and sedentary people,
African Americans, Alaska Natives, American Indians, Asian
Americans, Native Hawaiians, some Pacific Islander Americans,
and Hispanic Americans.
Common
typos:
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diabeets, diabtees, diaebtes, dibaetes, idabetes, iabetes,
diaete, diabete, daibete, daibetes, dyabetes,
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