you or someone you love has diabetes, you discover
that you must think about a part of life that others
take for granted. Your never-changing goal becomes
reaching a subtle balance between glucose and insulin.
The more learn about diabetes, the better you can
be at your balancing act, and the richer your life
shared with this chronic disease can be.
refers to a set of several different diseases. The
most common types of diabetes are type 1, or immune-mediated
diabetes mellitus, and type 2, or insulin - resistant
diabetes mellitus. A third type of diabetes, gestational
diabetes mellitus, occurs during some pregnancies.
All types of diabetes have similar symptoms, because
all forms of the disease result in too much sugar,
or glucose, in the blood. This is because your body
is unable to remove glucose from your blood and deliver
in to the cells in your body. Your cells use glucose
as a source of energy in order to say alive. But the
reasons why your body cannot use glucose from the
blood are different for type 1 and type 2 diabetes.
People with type 1 diabetes do not make enough insulin.
Insulin is a small protein made by the pancreas that
helps the body use or store glucose from food. People
with type 1 diabetes can be treated with injections
of insulin. In contrast, people with type 2 diabetes,
like women with gestational diabetes, do make insulin,
but for some reason, the cells in their bodies are
resistant to insulin's action or they don't make enough
insulin. In all types of diabetes, if glucose does
not get into the cells and tissues that need it, it
accumulates in the blood.
About half of all cases of type 1 diabetes appear
in childhood or in the early teenage years. For this
reason, it used to be called juvenile-onset diabetes.
If your symptoms first appeared during the early teenage
years, your doctor probably suspected diabetes right
away. If you were a young child when the disease developed,
it might have occurred so fast that you went into
a coma, before anyone suspected diabetes. Type 2 diabetes
most often develops in adulthood and used to be called
adult-onset diabetes. Usually, it does not appear
suddenly. Instead, you may have no noticeable symptoms
or only mild symptoms for years before diabetes is
detected, perhaps during a routine exam or blood test.
Gestational diabetes only appears during pregnancy
in women with no previous history of type 1 or type
2 diabetes and goes away after pregnancy. Pregnant
women are tested for gestational diabetes.
All people with diabetes have one thing in common.
They have too much sugar, or glucose, in their blood.
People with very high or poorly controlled blood glucose
level share many similar symptoms.
frequent desire to urinate
feeling of being tried most of the time for no apparent
with type 2 diabetes may also experience leg pain
that may indicate nerve damage or poor circulation.
Many people with type 1 diabetes and some people with
type 2 diabetes also find that they lose weight even
though are hungrier than usual and are eating more.
Even if they have lost weight, people with type 2
diabetes still tend to be overweight. Three-fourths
of all people with type 2 diabetes are or have been
obese - that is, they are at least 20 percent over
their desirable body weight. Type 2 diabetes tends
to develop in people who have extra body fat. Where
you carry your excess fat may determine whether you
get type 2 diabetes: Extra fat above the hips is riskier
than fat in the hips and thighs for developing for
2 diabetes. And leading an inactive "couch potato"
lifestyle can also leads to diabetes. It also contributes
If you have recently been diagnosed with diabetes,
you are not alone. Nearly 16 million Americans - about
one of every 17 people - have the disease. About 1,800
new cases each year. Ninety to ninety-five percent
of all cases of diabetes in people over age 20 are
type 2 diabetes. And half of all people with type
2 diabetes are unaware they even have the disease.
Because of the nature of type 2 diabetes, it is possible
to have mild symptoms or signs of type 2 diabetes
for years before diabetes worsens. In contrast, few
cases of type 1 diabetes go undetected to long. The
symptoms of type 1 diabetes are severe enough that
the person goes to the doctor for help.
16 million Americans have diabetes. This is about
6 percent of the people in the country. In 1999, it
was estimated that 500,000 to 1 million people had
type 1 diabetes. It is hard to get an exact count
of the number of people with diabetes because we have
no nationwide diabetes registry. Slightly under half
of the people with type 1 diabetes are children and
teenagers age 20 and younger. Type 1 diabetes is more
common in whites than in African Americans, Hispanic
Americans, Asian Americans, and Native Americans.
1999, it was estimated that about 9.5 million people
had diagnosed type 2 diabetes. Another 5 to 6 million
people are undiagnosed. It is common in older people.
Nearly 11 percent of Americans age 65 to 74 have type
2 diabetes. It is more common in some ethnic groups
than others. In American age 45 to 74, over 14 percent
of Mexican Americans and Puerto Rican Americans have
type 2 diabetes, over 10 percent of African Americans
have type 2 diabetes, and about 6 percent of Cuban
Americans and whites have type 2 diabetes. Type 2
diabetes is even more common in Nature Americans:
In some groups, almost half of adults age 30 to 64
have type 2 diabetes.
About 135,000 women develop gestational diabetes each
year. Of these, about 40 percent get type 2 diabetes
within 15 years.
your physician may suspect that you have diabetes
because of your symptoms, the only sure way to tell
is with blood tests. Blood tests are used to diagnose
both type 1 and type 2 diabetes, as well as gestational
diabetes. Your doctor may repeat your blood tests
to be sure of the diagnosis.
The blood tests are based on the fact that diabetes
keeps your blood glucose, or sugar, levels above normal
some or all of the time. Your blood glucose levels
may be high even though you haven't eaten recently.
In addition, your body cannot get rid of the extra
glucose that appears in the blood after eating.
Random plasma glucose tests are the simplest way to
detect diabetes. This test measures the amount of
glucose in the blood at any given time and is done
without fasting. If you have obviously symptoms of
diabetes and the amount of glucose in your blood is
200 mg/dl or higher, your doctor will diagnose diabetes.
Symptoms of diabetes include frequent urination, intense
thirst, blurred vision, unexplained weight loss, and
preferred method for diagnosing diabetes is the fasting
plasma glucose test. For this test, your doctor will
ask you not to eat for at least 8 to 10 hours. Then,
a sample of your blood is taken, and the amount of
glucose present in the blood is measured. Normally
after fasting, the amount of glucose is less than
126 mg/dl, the doctor will suspect diabetes. In diabetes,
extra glucose remains in the blood, even after fasting,
because it cannot enter the body's cells. This is
due to a lack of insulin or resistance to the action
of insulin. Doctors usually make a firm diagnosis
of diabetes when two fasting plasma glucose tests,
done on different days, are over 126 mg/dl.
If your test results are greater than 110 mg/dl but
less than 126
mg/dl, you may be diagnosed with impaired fasting
glucose. This is not diabetes, but sometimes occurs
before diabetes, usually type 2 diabetes, develops.
Some people with impaired glucose tolerance nerve
get diabetes. However, some of the same problems that
result from having diabetes also occur in people with
impaired glucose tolerance. If you have been diagnosed
with impaired glucose tolerance, your physician will
want to watch carefully for diabetes. Also, you need
to talk with your doctor about reducing your risk
of heart disease, keeping your weight in the healthy
range, and exercising regularly to lower your chances
of developing diabetes.
Not Sure Which Type of Diabetes You Have?
I have type 1 diabetes?
I have type 2 diabetes?
10 at diagnosis
20 at diagnosis
30 at diagnosis
40 at diagnosis
50 at diagnosis
60 at diagnosis
70 at diagnosis
weight at diagnosis
weight at diagnosis
amount of ketones in urine from time to time
history of type 1 diabetes
history of type 2 diabetes
oral diabetes medication
for the first few months, if at all
no diabetes medication
Certain pregnant women with no history of diabetes
are at high risk for developing gestational diabetes.
These are women who are 25 years of age or older,
are overweight, have a patient or sibling with diabetes,
or are Hispanic, Native American, Asian, or African-American.
If you have nay of these characteristics, your obstetrician
will screen you for gestational diabetes with a glucose
challenge. This is done between the 24th and 28th
weeks of pregnancy. At this time, the hormones of
pregnancy naturally begin to cause temporary insulin
resistance that lasts until the baby is born. The
glucose challenge helps your doctor determine whether
your body is able to overcome the insulin resistance
on its own. You are given a glucose drink to finish
at a certain time, without regard to eating. If the
glucose in your blood 1 hour later is 140 mg/dl or
above, you may have gestational diabetes. Your doctor
will need to give you another test, for which you
may need to fast, for a firm diagnosis.
1 OR TYPE 2?
tests reveal that you have diabetes, your doctor must
then decide whether you have type 1 or type 2 diabetes.
Although the symptoms and blood test results are similar
for both type 1 and type 2 diabetes, the cause are
DIABETES : FACT OR MYTH?
"I used to have type 2 diabetes,
but now I have type 1 diabetes. My doctor put me
on insulin last year".
Lot of people, over 40 percent of adults with diabetes,
use insulin. But because there are about 90 adults
with type 2 diabetes to every 5 adults with type
1 diabetes, this means there are a lot of people
with type 2 diabetes must use insulin to make up
for their pancreas no longer making it. You don't
necessarily have type 1 diabetes just because you
have to take insulin. Many people with type 2 diabetes
need extra insulin to overcome their body's resistance
to the insulin already being made by the pancreas.
Type 1 diabetes and type 2 diabetes, while having
a lot in common, are two different disease. They
have different causes. The type of diabetes you
have does not change as you age or if you lose or
gain weight or change treatment.
It will help your doctor to know whether there has
been type 1 or type 2 diabetes in your family. Your
age is not the only clue about what type of diabetes
you have. It's true that most people younger than
age 20 who show signs of diabetes have type 1 diabetes
and that most people diagnosed with diabetes when
they're over age 30 have type 2 diabetes. But there
are exceptions. In some cases, families carry a genetic
trait for developing type 2 diabetes as young people.
And in some Native American families, obesity is so
prevalent that children as young as 10 years old have
type 2 diabetes.
you are overweight or obese, it is more likely that
you have type 2 diabetes.
you suddenly developed signs of diabetes, such as
frequent urination, unusual thirst and hunger, and
weight loss, perhaps after an illness, and are a
young adult or child, it is more likely that you
have type 1 diabetes.
you are not overweight and there are ketones in
your urine, it is more likely that you have type
you are African American or Hispanic American, are
older than 50, are overweight, and haven't been
feeling quite "right" for along time,
it is more likely that you have type 2 diabetes.
your doctor treats you with insulin injections,
you could have either type 1 or type 2 diabetes.
WHO GETS DIABETES?
risk factors associated with type 1 or type 2 diabetes
are different. For both type 1 and type 2 diabetes,
having a family hisotry of diabetes puts you at a
higher risk for developing the disease than for a
person with no family hisotry of diabetes. However,
many people with type 1 diabetes have no known family
history of the disease. Type 1 diabetes is more common
among whites than among members of other racial groups.
In contrast, members of Native American, African American,
and Hispanic ethnic groups are at higher risk for
developing type 2 diabetes. Perhaps the genetic make
up of nonwhites predisposes them to the obesity and
diabetes that tend to result from a 20th century sedentary
A major difference in the characteristics of individuals
with type 1 and type 2 diabetes is the age of onset.
Typically, type 1 diabetes develops in individuals
under the age of 40. Half of all people diagnosed
with type 1 diabetes are under the age of 20. In contrast,
most of the
diagnosed with type 2 diabetes are over the age of
30, although type 2 diabetes is on the rise in teenagers.
The risk for type 2 increases with age. Half of all
new cases of type 2 diabetes ae in people age 55 and
Type 2 diabetes is more common in overweight and obese
individuals, whereas body weight does not seem to
be a risk factor for type 1 diabetes. Type 2 diabetes
is often found in women with a history of giving birth
to babies weighing more than 9 pounds an din women
who were previously diagnosed with gestational diabetes.
In both men and women, high blood pressure and very
high concentrations of fats in the blood are more
common in people with type 2 diabetes.
You can't get diabetes - either type 1 or type 2 -
from stress, exposure to someone who already has diabetes,
or from something you ate. And although diabetes may
reveal itself after an illness or a stressful experience,
these may have only speeded up the appearance of the
OF TYPE 1 DIABETES
people with type 1 diabetes, the immune system mistakenly
destroys the insulin - producing beta cells in the
pancreas, treating them as if they were a foreign
invander. This is called an autoimmune response. Autoimmune
responses also occur in other disease such as multiple
sclerosis, lupus, and thyroid diseases like hypothyroidism
and hyperthyroidism. Researchers do not know exactly
why this happens. But for diabetes, researchers have
found many factors that appear to be linked to type
1 diabetes. These include genetics, autoantibodies,
viruses, cow's milk and oxygen free radicals.
have long suspected that heredity plays a role in
diabetes, especially in type 1 diabetes. This is because
type 1 diabetes seems to run in families - if your
mother or father had diabetes for example, you are
more likely to develop the disease that someone without
a family history. Also, type 1 diabetes seems to be
more common in certain racial groups. Whites, for
example, are more likely to develop the disease than
are people from other racial backgrounds. Type 1 diabetes
occurs in less than 1 in 100,000 people in Shanghai,
China, but occurs in greater than 35 in 100,000 people
Everyone is born with a set of instructions that tells
the cells in your body how to grow live, and function.
These instructions lie in the particular chemical
sequence of units known as bases that make up the
DNA in every cell in your body. Each cell in your
body contains 46 chromosomes, which are made up of
DNA of protein. Each DNA strand is like a long string
that contain millions of bases. Along the strand lie
the genes, unique segments of DNA that tell you cells
what kind of protein to make.
But just as books sometimes contain typographical
errors, so too does the sequence of DNA. If there
is a mistake, or mutation, in the DNA within a gene,
then a faulty protein may be made that can't do its
job. Scientists are trying to determine how to mistakes
in specific genes cause diabetes. If mutated genes
occur in germ cells - the eggs and sperm - then the
DNA mutations can be passed on from generation to
Researchers have identified several different genes
that might make a person more likely to develop type
1 diabetes, However, they have not found one single
gene that makes all people who inherit it develop
the disease. Instead, it sems that there are several
genes known as "diabetes susceptibility"
One particular set of genes that may predispose a
person to diabetes is responsible for the human leukocyte
antigens, or HLAs. These genes code for certain proteins
called antigens, which identify a person's own cells
as "self". They tell the immune cells not
to destroy the cells that are part of person's body.
Scientists believe that some HLA antigens incorrectly
identify the beta cells as non-self. Then the immune
cells, which normally destroy froeign invading cells,
destroy these cells. This called autoimmunity - an
immune attack on a person's own cells. In type 1 diabetes,
the insulin - producing cells of the pancreas are
destroyed in an autoimmune attack, and the body can
no longer make insulin. This destructive process occurs
over many months.
Each person has many kinds of HLA genes, and thus
there are many typesof HLAs. Each person inherits
one of each kind of HLA gene from each parent. One
type of HLA gene, known as HLA-DR, is most strongly
linked to type 1 diabetes. There are many variations
of HLA-DR, but 95 percent of people with type 1 diabetes
have the DR3 form, the DR4 form, or both. This makes
researchers suspect that having the DR3 and DR4 variants
may make a person more likely to get type 1 diabetes.
However, this is not the whole answer, because 45
percent of people without type 1 diabetes have the
DR3 or DR4 variants. Also, variants of another HLA
gene, known as HLA-DQ, may also play a role in type
Just because a person inherits a susceptible HLA variant
doesn't mean that person witll develop diabetes. Most
people with DR3 or DR4 variants remain helathy. But
if there is a family hisotry of type 1 diabetes, then
screening may help predict the risk of developing
the disease. For example, borthers and sisters of
a person with diabetes who have two of the same HLA-DR
variants have a 15 percent chance of getting type
1 diabetes. But if they share only one variant, the
risk is only 5 percent. If no variants are the same,
the risk of developing type 1 diabetes is 1 percent
The more we study how people get type 1 diabetes,
the more we understand that the answers are not simple.
No one event or characteristic seems to bring on diabetes.
Researchers have identified several other gene clusters
on different chromosomes in addition ot these HLA
variants that may also play a role in type 1 diabetes.
immune system protects you from disease by killing
germs and other foreign invaders. It does this largely
through the action of white blood cells, or lymphocytes.
T lymphocytes, or T cells, can attack foreign cells
directly. B lymphocytes, or B cells, produce special
proteins called antibodies that recognize this shapes
of molecuels on the surface of specific invaders.
B cells sometimes manufacture antibodies that recognize
a person's own cells. These self recognizing antibodies
are called autoantibodies. Autoantibodies are found
in many people with autoimmune disorders, but three
autoantibodies are especially common in people with
type 1 diabetes. These antibodies recognize :
cells (beta cells are just one type of islet cell
in the pancreas)
acid decarboxylase, a protein made by the beta cells
in the pancreas. This protein is also called GAD,
or the 64K protein.
three types of autoantibodies all seem to act as markers.
Researchers believe that these antibodies contribute
to the demise of the beta cells of the pancreas by
identifying which cells are to be attached. It is
really the T cells that ultimately destroy the insulin
- producing cells of the pancreas. Of people newly
diagnosed with type 1 diabetes, 70 to 80 percent have
antibodies to islet cells, 30 to 50 percent have anitbodies
to insulin, and 80 to 95 percent have antibodies to
antibodies may be present several years before diabetes
is dagnosed. The islet cell antibodies disappear later
on. Because these antibodies are so common in people
with type 1 diabetes and because they so often appear
before the symptoms of diabetes appear, researchers
are finding that theya re useful in screening people
for type 1 diabetes who are at high risk for the disease.
Although the risk for developing diabetes may only
be 1 to 10 percent for people with a parent or sibling
with the disease, a much higher percentage of people
who also have antibodies to islet cells develop type
1 diabetes within 5 years. And for many, having combinations
of these antibodies and certain HLA genes results
in an even higher risk.
testing relatives of people with type 1 diabetes for
autoantibodies, doctors and researcheres can often
predict who is likely to develop the disease. This
could be especially useful as new therapies emerge,
because they can be strated before damage to the pancreas
is too extensive. For example, by identifying people
who are likely to develop type 1 diabetes at are early
stage, researchers may be able to treat with insulin
or drugs that suppress the immune system and thus
prevent the T cells from destroying the beta cells
in the pancreas.
people with a high risk of getting type 1 diabetes
have participated in studies to see whether immunosuppressants
such as azathioprine or cyclosporine delay or prevent
the onset of the disease. Researchers are also testing
to see whether long-acting insulin, oral insulin,
or nicotinamide can delay or prevent diabetes. These
studies suggest that axathioprine or cyclosporine
can reduce the dose of insulin needed in people who
have already developed type 1 diabetes, if the drug
is started at the time the disease is diagnosed.
therapies may also be tested as researchers learn
more about how autoantibodies contribute to diabetes.
For example, if autoimmunity to GAD turns out to be
a primayr trigger of type 1 diabetes, it might be
possible to develop a vaccine that would protect people
from developing the disease.
surprisingly, many scientists also suspect that viruses
may cause type 1 diabetes. This is because people
who develop type 1 diabetes have often recently had
a viral infection, and "epidemics" of type
1 diabetes often occur after viral epidemics. Viruses,
like those that cause mumps and German measles and
Coxsackie family of viruses, which is related to the
virus that causes polio, may play some role in cauisng
type 1 diabetes.
A small region of the GAD molecule is almost identical
to a region of a protein found in the virus known
as Coxsackie B4. The two similar protein regions probably
have similar shapes and may be recognized by the same
T cells. Thus, to a T cell hunting for foreign invaders,
the GAD protein, which is part of the body, might
look the same as the Coxsackie virus protein, which
is part of an invading cell. After a viral infection
by the Coxsackie virus, the T cell, bent on destroying
the invading virus, might actually destroy the body's
own beta cells that bear the GAD protein. This would
destroy the cells that produce insulin and result
in type 1 diabetes.
Other theories may also explain how a viral infection
might lead to diabetes. Some researchers believe that
when a virus in fects a body, it might somehow change
the structure of the antigens on the surface of the
islet cells. If this occurs, then the altered antigen
might appear to be foreign to the immune system, and
a person's own insulin-producing islet cells might
Gian Franco Bottazzo, a well-known diabetes researcher,
has another theory. He believes that diabetes is a
relatively new disease caused by a slow acting virus.
Although such a virus has not been found, Bottazzo
holds that the virus causes the immune system to attack
proteins in the pancreas. A drastic increase in the
number of cases of type 1 diabetes occurred on the
island of Sardinia, Italy, in the 1960s and in Finland
in the 1970s, and he believes that such a slow-acting
virus could be the culprit.
seems unlikely, but different kinds of food may pay
a role in the development of type 1 diabetes. For
example, one group of researchers found a connection
between being fed cow's milk early in life and type
1 diabetes. They showed that children newly diagnosed
with type 1 diabetes have higher amounts of antibodies
that recognize a specific protein in cow's milk. These
autoantibodies appear to bind to a protein that sometimes
appears on the surface of the insulin-producing beta
cells int eh pancreas after an illness. The researchers
speculate that, after an illness, the transient protein
may appear on the surface of beta cells. The immune
response to the milk protein might be to then recognize
the beta cell surface proteins and attack the beta
cells, leading to a destruction of the insulin - producing
cells of the pancreas, and thus, to type 1 diabetes.
However, other researchers have looked for but not
found an increased risk of type 1 diabetes if cow's
milk is given early in life and if breast feeding
is done for a short period. Cow's milk is only one
kind of food that may play a role in the development
of type 1 diabetes. Studies in diabetes - prone rats
show that withholding wheat and soy helps delay or
these are not part of some terrorist organization,
but they may as well be. Oxygen free radicals, formed
a s a by product of many chemical reactions in the
body, wreak havoc wherever they go. Normally, the
body has ways of quenching free radicals. But smoke,
air pollution, diet, and even genetics can be contribute
to the formation of excessive amounts of free radicals,
which the body cannot always handle. Uncontrolled,
the reactive molecules can destroy the body's own
cells as well as bacteria. Oxygen free radicals contribute
significantly to the aging process and to the development
of several other diseases. Researchers have implicated
free radicals in the development of amyotrophic lateral
sclerosis (ALS), or Lou Gehrig's disease, a degenerative
Some researchers believe that oxygen free radicals
may also contribute to type 1 diabetes. Islet cells
have very low levels of the enzymes that break down
free radicals. Thus, agents that increase free radical
production could result in destruction of pancreatic
cells. If this is true, then researchers may be able
to develop drugs that block the formation of free
radicals in the islet cells.
chemicals have been shown to trigger diabetes. Pyriminil,
a poison used to kill rats, can trigger type 1 diabetes.
Two prescription drugs, pentamidine, used to treat
pneumonia, and L-asparaginase, an anticancer drug,
can also cause type 1 diabetes. Other chemicals have
been shown to make animals diabetic, but scientists
don't know for sure whether they have the same effect
It is unlikely that either genetics or environmental
factors alone cause diabetes. But it does appear that
a person could start with a genetic susceptibility
- the inheritance of a particular set of genes. If
this person is then exposed to some environmental
"triggering" factor, such as a virus or
a chemical, then diabetes may develop. Although no
one is destined to develop diabetes with certainty,
a person's heredity increases the odds.
OF TYPE 2 DIABETES
reasons that type 2 diabetes occur are different from
those that trigger type 1 diabetes. Unlike people
with type 1 diabetes, who become unable to produce
insulin, people with type 2 diabetes produce insulin.
But, either the body does not respond to insulin's
action - it's resistant - or there is just not enough
insulin to go around - there's too much body for the
amount of insulin that's made. Either problem leads
to the same outcome: insulin can't deliver glucose
to the cells that need it, and there's too much glucose
in the blood.
Virtually all cells in the body contain special proteins
called receptors that bind to insulin. They work like
a lock and key. In order for glucose to enter the
cell, insulin must first fit into the insulin receptor.
But for some reason, in some people with type 2 diabetes,
there is a faulty lock, or insulin receptor. The key
doesn't open the lock, and glucose is shut out of
the cell. And in some people with type 2 diabetes,
there are not enough locks, or insulin receptors,
on the cells to allow enough glucose to enter. But
for most people with diabetes it's not so much that
the key doesn't fit the lock, but that insulin doesn't
work properly. In rare cases, the insulin is mutated,
or built incorrectly, and does not fit the insulin
In addition to problems with insulin and the insulin
receptor, in many people with type 2 diabetes, the
beta cells in the pancreas do not produce enough insulin.
Without enough insulin to meet the body's needs glucose
level rise and diabetes results. Scientists do not
know why the pancreas does not function well in these
people. Some believe that the system that controls
glucose levels in the blood and tells the pancreas
to make more insulin does not function properly. Other
think that the pancreas, after many years of working
overtime, overproducing insulin to overcome insulin
resistance, simply begins to "burn out."
Although researchers do not fully understand why type
2 diabetes develops, they have uncovered many factors
that may contribute to the disease.
also appear to play a role in how type 2 diabetes
develops. Like type 1 diabetes, type 2 diabetes also
appears to run in families, and it is most likely
due to the inheritance of certain genes. The link
to genetics seems even stronger in type 2 diabetes
than in type 1 diabetes. If a person with type 1 diabetes
had an identical twin, there is a 25 to 50 percent
chance that the twin, will develop diabetes. But if
a person with type 2 diabetes has an identical twin,
there is 60 to 75 percent chance that the person will
More evidence for the role of genes in type 2 diabetes
comes from studying minorities. Compared with whites,
African Americans, Asian Americans, Hispanic Americans,
and Native Americans all get type 2 diabetes more
often. Native Americans have the highest rate of type
2 diabetes in the World. Hispanic groups, such as
Mexican Americans, that share genes with Native American
groups have a higher rate of type 2 diabetes than
Hispanic groups, such as Cuban Americans, where less
intercultural contact has occurred.
Researchers have not yet isolated a single "type
2 diabetes" gene, but they are finding errors
in several that may contribute to type 2 diabetes.
For example, researchers have identified a protein
called PC-1 that shuts down the insulin receptor,
which creates insulin resistance. This protein is
prevalent in most people with type 2 diabetes, compared
with people without diabetes. For some reason, too
much of the inhibitor protein is made in some people,
and the insulin receptor cannot do its job properly,
which can lead to insulin resistance.
Researchers believe that the genes that lead to obesity
may also play a role in diabetes. In mice, scientists
have identified a gene they called the obese gene.
The obese gene appears to regulated body weight by
making proteins that affect the center in the brain
that tells you whether you're full or hungry. When
the obese gene is mutated, the mice become obese and
develop type 2 diabetes.
OBESITY, AND LIFESTYLE
most important environmental trigger of type 2 diabetes
appears to be obesity. Obesity is defined as weighing
more than 20 percent over your desirable body weight.
Genetics may play a role in obesity and, thus, in
triggering type 2 diabetes.
In some way, having too much body fat promotes resistance
to insulin. This is why, for so many years, type 2
diabetes has been treated with diet and exercise.
Losing weight and increasing the amount of muscle
while decreasing the amount of fat helps the body
use insulin better. There is also a link between type
2 diabetes and where your body is too fat. People
with central body obesity, which means carrying excess
fat above the lips, have a higher risk of developing
type 2 diabetes than those with excess fat on the
hips and thighs.
Central body obesity, as well as overall obesity,
is more common in African Americans than in whites.
This may be one reason why type 2 diabetes is also
more common in African Americans than in whites.
Age also appears to play a role. Half of all new cases
of type 2 diabetes occur in people over age 55. Because
people tend to gain weight as they age, many researchers
think that the reason more older people develop diabetes
is because more older people are overweight.
Leading an inactive, sedentary lifestyle and consuming
a high-calorie diet can also lead to type 2 diabetes,
presumably by contributing to obesity. Obesity, as
well as type 2 diabetes, are common in Asian Americans
and Hispanic Americans who have "westernized"
their eating and activity habits.
OF GESTATIONAL DIABETES
the other types of diabetes, the exact cause of gestational
diabetes is unknown. However, experts do have some
pregnancy, the placenta, which is the organ that nourishes
the growing baby, produces large amounts of various
hormones. Hormones are important for the baby's growth.
However, these hormones may also block insulin's action
in the mother's body, causing insulin resistance.
All pregnant women have some degree of insulin resistance.
Gestational diabetes usually appears around the 24th
week of pregnancy. This is when the placenta begins
producing large quantities of the hormones that cause
insulin resistance. For this reason, the period between
the 24th and 28th weeks of pregnancy is a good time
to screen for gestational diabetes.
insulin resistance, rather than underproduction of
insulin, seems to cause gestational diabetes it is
more like type 2 diabetes than type 1 diabetes. And
having gestational diabetes increases your chances
of someday developing type 2 diabetes. Researchers
suspect that the genes responsible for type 2 diabetes
and for gestational diabetes may be similar.
Some women show signs of high blood glucose even before
the 28th week of pregnancy. Doctors believe that these
women probably had diabetes that was unrecognized
before the pregnancy began. The weight gain and hormonal
changes of pregnancy stressed the body and revealed
the diabetes. This can happen with either type 1 or
type 2 diabetes. Doctors would carefully watch what
happens after the pregnancy in order to diagnose type
1 or type 2 diabetes.
diabetes is more common in groups that have more obesity.
For instance, it is found more often in areas with
a large number of Hispanic Americans, in whom obesity
is more common. Obesity can trigger gestational diabetes
as well as type 2 diabetes.