Diabetes
A Major Risk Factor For Heart Disease.
Diet, Exercises and Lifestyle changes
can reduce the risk of diabetes mellitus a chronic disease in which
the pancreas produces too little or no insulin, impairing the body's
ability to turn sugar into usable energy.
This article emphasizes the importance of determining
our risks, and of the necessary measures to take to avoid getting
it and to treat it through proper diets and exercises.
Diabetes: A Growing Public Health Concern
By Carol Lewis (staff writer for FDA Consumer
Magazine)
Either you have it or you don't.
That's the message that the American Diabetes
Association (ADA) is driving home to millions of people who believe
they may be "borderline diabetic," or that their "sugar is just
a bit high."
Convenient phrases and stereotypes such as these
don't adequately describe one of the nation's leading causes of
death and disability. In fact, they tend to only minimize problems
associated with the disease.
The bottom line? An accurate diagnosis is essential,
because while a person can live a long and healthy life with diabetes,
ignoring it or not taking it seriously can be deadly.
It's deadly you must pay attention to it
"It's crucial to know when you have it,
to hear the diagnosis, and to pay attention to it," says ADA president
Christopher D. Saudek, M.D.
Saudek, who also heads up the diabetes center
at Johns Hopkins University School of Medicine in Baltimore, says
he's seen people deny it "almost to the point of death."
What is it?
Diabetes mellitus is a chronic disease in which
the pancreas produces too little or no insulin, impairing the body's
ability to turn sugar into usable energy. Doctors often use the
full name "diabetes mellitus," to distinguish this disorder from
diabetes insipidus--a different disease altogether that is characterized
by excess urination, but is unrelated to blood sugar.
How prevalent is it?
The number of people diagnosed has increased
more than six fold from 1.6 million in 1958 to 10 million in 1997,
according to the Centers for Disease Control and Prevention (CDC)
in Atlanta. Today, some 16 million people have the disease--making
it a leading cause of death in the United States--yet 5 million
don't know they have it. And nearly 800,000 new cases diagnosed
each year.
There is no cure
There is no cure for the disease, and the resulting
health complications from poorly controlled diabetes are what make
it so frightening. Consistently high blood sugar levels can, over
time, lead to blindness, kidney failure, heart disease, limb amputations,
and nerve damage.
In fact, it is the leading cause of new cases
of blindness in adults between the ages of 20 and 74, and it accounts
for 40 percent of people who have kidney failure.
Cardiovascular disease is 2 to 4 times
more common among people with the disease, and is the leading cause
of diabetes-related deaths. Cardiovascular disease is 2 to 4 times
more common among people with the disease, and is the leading cause
of diabetes-related deaths.
The risk of stroke is also 2 to 4 times higher,
and 60 percent to 65 percent have high blood pressure.
It can be well managed through lifestyle
changes, exercise and diet.
Despite these numbers, Saudek says it can be
very well-managed and that people can expect to live full and productive
lives. Much of the treatment, however, depends largely on self-care
practices. It's important, Saudek says, not only to target good
behaviors, but also to consistently follow through with them.
Monitoring blood sugar levels is a key component
in treatment and management of the disease. Research has indicated
that people who keep their blood sugar levels within individual
target ranges set by their doctors stand a good chance of reducing
the risks and complications.
Moreover, in many cases intensive lifestyle changes
in diet and exercise actually can prevent, reduce or delay the risk
of developing one type of the disease.
Understanding Diabetes
Blood sugar, or blood glucose, refers to the amount
of sugar in the blood. The brain's only food is glucose; therefore,
blood sugar must be maintained at a certain level for the brain
to function normally.
After eating any meal that contains carbohydrate
or protein, a person's blood sugar normally rises, often to between
120 and 130 milligrams per deciliter (mg/dL), but generally not
above 140 mg/dL. Every day, every hour, blood sugar levels vary,
even in people who aren't diabetic.
If the blood sugar level drops too low (hypoglycemia),
a person's ability to reason can become impaired. When the blood
sugar levels are too high (hyperglycemia), diabetes is diagnosed.
Symptoms
Often the diagnosis is obvious to doctors because
symptoms such as thirst, fatigue, weight loss, frequent urination,
and persistent vaginal infections in women are evident.
In the presence of these symptoms, it can be
confirmed by a random test of blood sugar, meaning that the blood
is drawn at any time during the day, rather than specifically before
eating breakfast.
If the person is thirsty and urinating large
amounts, the blood sugar usually will be well over 200 mg/dL, sometimes
up in the 300s and 400s, or higher.
But when the classic symptoms are not present,
the criteria for diagnosing it include a fasting blood glucose test.
This means that the blood glucose is drawn at
least 10 hours following a meal early in the morning, when it is
usually at its lowest point in the day.
A random blood glucose higher than 200 mg/dL
and a fasting glucose of 125 mg/dL or more confirms a diagnosis
of diabetes.
Insulin and the pancreas
To understand diabetes it's important to know
something about insulin. Insulin is a hormone made in the pancreas,
a large, elongated gland located behind the stomach.
Its purpose is to "unlock" the cells of the body
so that glucose carried by the blood can be used for energy. When
you eat carbohydrates, your blood sugar rises.
This increase triggers a release of insulin from
cells in the pancreas called beta cells. The insulin "opens the
doors" of the cells throughout the body to glucose. As glucose enters
the cells, the blood sugar level falls back to normal--and the release
of insulin ebbs until the next time protein or carbohydrates are
eaten.
Type 1 and Type 2
The basic problem in type 1 is that the pancreas
quits making insulin.
In type 2, it either doesn't make enough or something
interferes with the action of the insulin that is made. Someone
with type 1 must inject replacement insulin to stay alive.
Blood sugar levels in type 2 usually are controlled
by drugs that lower blood sugar as well as diet and exercise. Sometimes,
injections of replacement insulin are needed to maintain normal
blood sugars.
The increasing emphasis on the importance
of reducing weight and other lifestyle changes, combined with the
latest advances in medical therapies, all have had dramatic effects
on diabetes control (see "Diet, Exercise Delay Type 2 Diabetes,"
September-October 2001 FDA Consumer).
While it is fairly easy to diagnose, determining
what type of diabetes a person has can be both challenging and critical.
An accurate diagnosis matters because there are
different ways to treat the different types in order to stave off
potential long-term complications.
Type 1 Diabetes
People with type 1, such as 56-year-old Paul Keister
of Arlington, Va., must inject replacement insulin to control the
levels of glucose in their blood. Frequent tests (several times
a day) using blood obtained from finger pricks are required to maintain
good blood sugar control.
In type 1 , the beta cells of the pancreas are
destroyed by the body's immune system, which is responsible for
recognizing and destroying outside invaders such as viruses or bacteria.
In a process that is not well-understood, the
body begins to think that its own pancreatic beta cells are "foreign"
and sets off an "autoimmune" response that ends up destroying the
cells. As a result, no insulin can be produced.
Type 1 accounts for 5 percent to 10 percent of
all people with the disease.
This type is sometimes called juvenile diabetes
because it most commonly appears initially in children or adolescents.
However, people older than 30 also may develop the condition.
Scientists believe that some environmental factor--possibly
a viral infection or something related to nutrition--causes the
immune system to destroy the insulin-producing cells.
At 30 years old, Keister was diagnosed with type
1 diabetes following a stomach illness and after a stubborn tooth
infection refused to go away.
The resulting insulin deficiency is usually severe.
Without injections of enough insulin to control increases in the
blood sugar, diabetic ketoacidosis (coma and potentially death)
can result.
Today, type 1 is treatable, and ketoacidosis
preventable by taking sufficient amounts of insulin and by following
dietary guidelines set by doctors and the ADA.
Type 2 Diabetes
Type 2 diabetes accounts for more than 90 percent
of cases in the United States. In this type, the pancreas continues
to produce insulin; however, the body develops resistance to its
effects, resulting in a different kind of insulin deficiency than
in type 1.
Although the blood sugar rises in type 2 for
different reasons than in type 1, the symptoms and potential complications
are similar.
Certain racial and ethnic groups, including blacks,
American Indians, Mexican-Americans and other Hispanics, are at
increased risk for getting the disease. And obesity is a risk factor
for type 2.
Although doctors don't know exactly why, they
say it's clear that the muscle cells (where most of the sugar breakdown
occurs) of obese people are far less responsive to insulin than
are muscle cells of thinner people.
An obese person's pancreas has to put out large
amounts of insulin to keep blood sugars normal. The likelihood of
developing type 2 in people who are at risk increases with age and
weight gain.
The typical person with type 2 is older, overweight,
and often has a family history of diabetes. Dale Driscoll of Frederick,
Md., was diagnosed with type 2 at about the same age that Paul Keister
was diagnosed with type 1--an indication that age alone is not a
reliable diagnostic criterion. And there is little evidence to suggest
that diabetes runs in Driscoll's family.
It's important, says Saudek, to know that some
people don't fit neatly into either of these diagnostic "boxes."
Like Driscoll, none of Keister's relatives on either parent's side
has ever had diabetes, even though type 1 occurs in people with
a genetic susceptibility. There are exceptions to the general rule
that diabetes occurring in the young is type 1, and that diabetes
occurring in older people is type 2. Likewise, taking insulin does
not mean you have type 1, just as obesity is not a sure diagnostic
sign of type 2.
Type 2 diabetes is nearing epidemic
proportions in the United States, according to diabetes experts,
due to an increased number of older Americans and a greater prevalence
of obesity and sedentary lifestyles.
Gestational Diabetes
Between 3 percent and 5 percent of pregnant women
in the United States develop gestational diabetes--elevated blood
sugar due to certain hormones that occurs only during pregnancy.
It is important to diagnose and treat gestational diabetes properly
because it increases the risk of a baby growing larger than he or
she would have been, and a large baby may have difficulty during
delivery, or may be born by cesarean section.
Keeping blood sugar within a normal range during
the pregnancy reduces these risks. Women who experience gestational
diabetes have a greater risk of developing diabetes later in life.
One large study found that more than half of women who had gestational
diabetes eventually developed type 2 diabetes. .
Controlling Diabetes--Treatment Goals
Daily monitoring and careful control of blood
sugar levels are the most important steps that people with diabetes
can take, says David G. Orloff, M.D., director of the FDA's division
of metabolic and endocrine drugs.
Over the past decade, "tight control" of blood
sugar with a goal of achieving and maintaining near-normal levels
has become the standard of care for both type 1 and type 2 diabetes.
Maintaining normal levels is difficult, Orloff says, "but good glycemic
control is key to preventing long-term complications."
Another reason for good blood sugar control,
Orloff adds, "is that it does make a difference in how people feel."
Joanna K. Zawadzki, M.D., of the FDA's metabolic
and endocrine drugs division, cautions that "just having a blood
glucose monitor is not adequate follow-up to your diabetic treatment."
People need better blood sugar control than just enough to avoid
symptoms, she says.
Keeping blood sugars always between 150 mg/dL
and 200 mg/dL, for instance, may help a person avoid obvious symptoms,
but may not be good enough to avoid the long-term complications.
"Diabetes treatment is a complex approach that comprises a team
of professionals, the patient, his or her family, and treatment
and goals agreed upon by the team." Zawadzki adds, "Work with your
doctor to come up with reasonable expectations for your individual
treatment plan."
People with type 1 diabetes need insulin from
the time they are initially diagnosed, throughout life. Type 2 diabetes
may often mean a prescribed regimen of diet and exercise in the
initial phases of the disease.
Frequently, however, and certainly over time,
changes in diet and exercise aren't enough to keep blood sugar at
near-normal levels. The next step for these people is taking a medicine
that lowers the blood sugar. There are two basic kinds: insulin
therapy and oral medications.
Insulin Replacement Therapy
Before the availability of insulin, treatments
for people with type 1 diabetes were unpleasant and often ineffective.
A low-carbohydrate, semi-starvation diet and exercise were all doctors
had to offer. People lost more and more weight, and many of them
died within the first year of diagnosis. Like many scientific advances,
the discovery of replacement insulin in the 1920s was nothing short
of a miracle.
Insulin lowers blood sugar by both increasing
the removal of glucose from the blood and reducing the production
of glucose by the liver. In type 1 diabetes, since there is virtually
no insulin produced by the pancreas, people need insulin all the
time--more at mealtimes to "cover" the carbohydrates and protein
eaten, and less during other times to maintain as even a level as
possible. In people with type 2 diabetes, insulin injections sometimes
are needed to supplement the amount produced by the pancreas.
Insulin injections are given under the skin (subcutaneously)
into the fat layer, usually in the arm, thigh, or abdomen. Insulin
cannot be given by mouth because it is destroyed by digestive enzymes
in the stomach. Small syringes with very thin needles make the injections
nearly painless. In recent years, several external insulin pumps,
which deliver insulin continuously through a thin, flexible tube
placed under the skin, have been developed.
There are more than 20 types of insulin available
in four basic forms, each with a different time of onset and duration
of action (see "Insulin Preparations."). The decision as to which
insulin to choose is based on an individual's lifestyle, a physician's
preference and experience, and the person's blood sugar levels.
Among the criteria considered in choosing insulin are: how soon
it starts working (onset), when it works the hardest (peak time),
and how long it lasts in the body (duration).
Oral Medications
Pills to treat diabetes--anti diabetic agents--are
used only in type 2 treatment. Four general classes of drugs work
in different ways to lower blood sugar (see "Oral Anti diabetes
Medications.").
There are some risks associated with the use
of these drugs. For example, sulfonylureas, which stimulate the
beta cells in the pancreas to release more insulin, can be associated
with severe low blood sugar levels, particularly when the person
has other medical problems or is taking other medications. And in
order for them to work, a person's pancreas must be making at least
some insulin. That is why oral medications will not work for the
treatment of type 1 diabetes.
For best results, oral medications must be taken
regularly every day, not irregularly or started and stopped according
to blood sugar. Since many dosages are available, a physician can
change the dosage if blood sugars are running too high or too low.
Many of these drugs can be used in combination with one another,
but any change in their use should be done only at the direction
of a health-care professional.
Driscoll's doctor found that oral medications
were not effective in controlling his blood sugar, and he replaced
them with insulin injections. In retrospect, Driscoll says, "while
the pills were easier to deal with, insulin has made the greatest
difference in my life." In addition, Driscoll has shed 40 of the
100 pounds recommended by his doctor as part of his treatment plan.
Organ Transplants
Pancreas transplants and kidney transplants are
options for people with type 1 diabetes, if they have kidney failure
(about one-third of type 1 patients). Since the 1970s, doctors have
performed pancreas transplants along with kidney transplants in
hopes of halting or reversing the complications of diabetes.
The procedure has met with some success. Kidneys
alone are transplanted to replace kidneys that have totally failed.
Pancreas transplants may be done simultaneously or after kidney
transplants, to try to "cure" diabetes.
But pancreases are often not transplanted unless
a kidney is also needed, says Saudek, "because the surgery is so
major and the need for continuous immune suppression is more dangerous
than taking insulin." Saudek adds that unavailability of transplantable
kidneys and pancreases also is a factor.
A kidney transplant for people with type 1 and
type 2 diabetes can restore the body's ability to perform a number
of crucial functions, including filtering wastes from the blood
and controlling the body's fluid and chemical balance. Receiving
a new pancreas at the same time may actually improve kidney survival.
In addition, a new pancreas can improve blood sugar levels to normal,
or close to it.
Organ transplants aren't always successful. Besides
the risk inherent in any major surgery, the body can reject the
new organ days or even years after the transplant. Because of this,
transplant recipients will likely need to take immunosuppressive
drugs the rest of their lives. The drugs themselves carry significant
health risks, such as cancer, but they work to prevent the immune
system from rejecting the new organ.
Other therapeutic interventions
Another noteworthy therapeutic intervention,
and one that Keister hopes to be considered for, is a procedure
called islet cell transplantation. Researchers have known for some
time that transplanting these insulin-producing cells may provide
a possible cure for type 1 diabetes. The process to date is still
not perfected, but there is some evidence that researchers may be
getting closer to their goal.
"From the biologics perspective," says
Philip Noguchi, M.D., director of the FDA's division of cellular
and gene therapy, "emphasis on products for diabetes is clearly
experimental at this time, but potentially very promising." In islet
cell transplantation, doctors extract islet cells from the pancreas
of a person who has recently died and then infuse them via a catheter
into the liver of the person with diabetes. The liver instead of
the pancreas is the location for the transplant because it is easier
and less invasive to access the large vein in the liver than a pancreatic
vein, and islet cells that grow in the liver closely mimic normal
insulin secretion.
Because the cells are very fragile, the procedure
is fraught with problems. One of the biggest obstacles is the availability
of fresh islet cells. There is a shortage of organ donors in the
United States, and the supply of islet cells, like kidneys and pancreases,
is limited. Another challenge is the ability to isolate the cells.
It takes several donor pancreases to isolate enough islet cells
for a single transplant.
Still, "when it comes to trying new treatments,"
says Keister, "I'm going to push the envelope." Since his diabetes
was detected prior to glucose meters, Keister says the greatest
contribution he can give back to society is his "participation in
new trials using the latest technology to learn more about the effects
of treatment on the disease."
While additional studies are underway to learn
more about the long-term effects of islet cell transplantation,
Noguchi says, "at the moment there are a number of well-established
procedures for type 1 and type 2 diabetes that let people live normal
lives."
Prognosis
Saudek says it's a scientific fact that the outlook
for people with diabetes can be excellent if the disease is well
taken care of. Several major studies, including the Diabetes Control
and Complications Trial Research Group, in which people with type
1 diabetes have been followed for years, compared the effects of
standard and more intensive diabetes treatments on the development
and progression of long-term complications. The more intensive treatments
prevented or slowed diabetes complications.
So, says Saudek, "It's doable. Taking advantage
of what's available puts people in the best possible position to
be strong and healthy when diabetes is ultimately cured."
Characteristics of Type 1 Diabetes
- Age of onset under 40 years old, most common
in children; some older people develop this type
- Thin to normal body weight
- Quick onset with thirst, frequent urination,
and weight loss symptoms developing and worsening over days to
weeks
- Usually no known family history, but in rare
cases there can be
- No major risk factors; risk is increased if
strong family history exists
- Usually more than one shot daily of insulin
treatment always needed to control diabetes
- Difficult to keep fluctuating blood sugar in
ideal range
- Blood sugar is sensitive to small changes in
diet, exercise, and insulin dose
- Can be caused by a combination of heredity and
exposure to some factor during life that triggers autoimmune destruction
of the insulin-producing beta cells in the pancreas
Characteristics of Type 2 Diabetes
- Age of onset over 40 years old, most common
in adults; some younger people develop this type
- Overweight; occasionally occurs in people of
normal weight
- Usually slow onset with thirst, frequent urination,
and weight loss symptoms developing over weeks to months, or even
years
- Can be "silent disease"
- Usually runs in families
- Treatment usually begins with diet and exercise,
progressing to pills and later to insulin
- Easier to control without fluctuating blood
sugar range
- Blood sugar may respond to weight loss, and/or
change in diet and exercise; blood sugar may be less responsive
to small changes in insulin dose
- Can be caused by combination of heredity, insulin
resistance, and deficiency of the insulin-producing beta cells
of the pancreas
--C.L.
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