Heredity | Viruses | Immune Responses | Honeymoon Period
Inslulin | Opening the
Cells | Locking the Cells | Starving in the Midst of Plenty | Regulation of Blood Sugar Levels | Injected Insulin |
Self Monitoring Blood Sugar Levels
Although diabetes mellitus has been known since ancient times, it is only recently that we
have begun to understand what causes it. We hope that eventually this understanding can
help us develop methods both to prevent and reverse the disease. More is now known than
ever before, but much is still to be learned.
Type I diabetes is a lifelong disease that prevents the body from properly regulating the
metabolism (breakdown, processing, and storage) of its fuels. The bodys fuels
include carbohydrates, proteins, and fats. However, carbohydrates are the bodys
preferred energy source. Once digested, carbohydrates are converted into glucose (sugar)
and provide the major fuel in the body.
The body can be viewed as a complex machine that performs many jobs. Through the carefully
controlled release of insulin, which is a hormone made in the pancreas, the body is able
to control how and when fats, proteins, and carbohydrates are broken down, stored, and
released. Insulin is released continuously by the pancreas in amounts that change
according to the needs of the body.
However, people with Type I diabetes have little or no insulin. As a result, they cannot
automatically perform this job. Without insulin, the body rapidly builds up levels of
ketones (breakdown products of the digestion of fats) in the blood that lead to rapid
breathing, coma, and then death. Until 1922, when insulin was first used to treat
diabetes, this happened to most people with Type I diabetes shortly after they were first
diagnosed. Today this can be prevented by treatment with insulin injections.
People can inherit genes that make them more likely to develop Type I diabetes. Several
years ago, scientists discovered that children with diabetes had certain proteins on the
surface of their cells. These proteins, called HLA antigens, help the body to recognize
and destroy invading bacteria and viruses. They also help to prevent the growth of
cancers. We inherit a total of 10 different HLA antigens, help the body to recognize and
destroy invading bacteria and viruses. They also help to prevent the growth of cancers. We
inherit a total of 10 different HLA antigens. Some seem to increase a persons risk
of developing diabetes, while others seem to decrease the risk.
Just having the dangerous HLA antigens, however, does not mean that someone will
definitely develop diabetes. In identical twins who have all the same genes, if one twin
already has Type I diabetes, the risk of the second twins developing it is only
Genes alone are not enough to explain why people develop diabetes; there must be some
non-inherited factor. Viruses may play a major role in triggering the onset of diabetes in
people who are likely to develop it based on their HLA antigens. Several viruses are
linked to the development of diabetes. The virus that causes German measles is one, but
other viruses seem to be involved, and not everyone with the right HLA antigens who
develops German measles comes down with diabetes.
The immune system is the bodys way of protecting itself from viruses, bacteria, and
the development of groups of cancer cells. There are two major parts to the immune system.
One part consists of specialized cells that are designed to recognize and destroy
"foreign" substances. The second part consists of special
proteins-antibodies-that are also designed to destroy foreign substances. Usually the
foreign substance will be attached by both antibodies and cells, often in that order.
In diabetes, soon after diagnosis, it is possible to find both antibodies and cells that
are designed to attack the insulin-producing cells of the pancreas. Which of these two
parts of the immune system is more important in finally destroying the insulin producing
cells is still uncertain. Some patients go for many years with these antibodies in their
blood before becoming diabetic. Many people with these antibodies in their blood never
The hope of research today is to find specific drugs that will attack those parts of the
immune system that are destroying the insulin-producing cells without interfering with the
rest of the immune system. As miraculous as this would seem to be, it may be possible in
One confusing feature at the onset of Type I diabetes is that a number of people with
diabetes have a "honeymoon period" after their diagnosis. The honeymoon period
is a period of time that can occasionally last up to a year, during which the newly
diagnosed needs either no insulin or very little insulin to control blood sugar. Many
people become fooled into thinking during this period that either they are not really
diabetic or that their diabetes will be very easy to take care of and will not require any
work on their part. When this period finally ends, many people have more trouble accepting
their diabetes than they had in the beginning.
One Type I diabetes develops; it is always treated with insulin. To better understand the
treatment, you need to know more about insulin, what it is and how it works. Insulin is a
hormone, a chemical made by the beta cells of the pancreas. Insulins main function
in the body is to make sure that the cells have enough fuels, or energy, to carry out
their daily activities. Insulin does this in two ways: First, it allows the foods that
have been digested by the stomach to move from the blood stream into the cells of the
body. Second, it controls the release of these foods back into the blood stream. In other
words, insulin works very much like a key. When you eat, insulin "opens" the
cells and allows the digested foods (carbohydrates, proteins, and fats) to move inside.
Between meals or whenever a person is not eating, insulin locks these same cells and
prevents the release of these foods back into the bloodstream.
Opening the Cells
Insulin is normally released into the bloodstream 24 hours a day, regardless of whether
the person is awake or asleep, eating or fasting. The largest amount is released when a
person eats. This insulin "opens" the cells. If the insulin is not present at
the time the food is eaten, the body will have difficulty moving the food out of the
bloodstream and into the cell. That person will have trouble keeping the sugar level in
the bloodstream from rising above that is normal (150 mg/dL) after a meal. Despite the
persons having just eaten, the cells will remain without food.
Locking the Cells
A smaller amount of insulin is secreted at all other times. The body needs a steady supply
of insulin, even if no food has been eaten for several hours or days. This insulin is
needed to "lock" the cells. If insulin is not present, the body will have
trouble preventing the release of the fuels (sugar, proteins, and fats) back into the
bloodstream. That persons blood sugar will increase even without eating.
Starving in the Midst of Plenty
In the person with Type I diabetes, the absence of insulin means that the cells will be
unlikely to get or keep enough fuels to supply their energy needs. Even though that person
continues to eat and may, in fact, be eating more than usual, without insulin the cells
cannot use the food. The cells literally begin to starve in the midst of plenty. The
person stays hungry even after eating because the foods digested by the stomach remain in
the blood stream and do not get into the cells. As the level of sugar in the bloodstream
increases, the body begins to pull water from the tissues into the bloodstream. The helps
to dilute the sugar-filled blood but leads to an increased thirst and drying of the skin.
Meanwhile, the kidneys begin to sense that the sugar level is too high. They start to push
the excess sugar along with water into the urine. This causes the person to urinate often
and in large amounts.
In an effort to obtain its needed supply of energy, the body begins to burn fats for
energy and sets in motion a chain of events that, if left unchecked, will lead to coma and
death. This is called diabetic ketoacidosis (DKA).
Regulation of Blood Sugar Levels
It might help to think of insulins two regulating functions in terms of a more
common fuel regulating system a thermostat. The body, like a thermostat, can lower or
raise the level of fuels, especially sugar. Like a thermostat, it has an automatic sensor
that monitors both the level of fuels in the bloodstream and the level of hormones that
control these fuels. The body has several hormones that respond to this sensor to make
sure that the fuel level goes neither too high nor too low. These hormones balance each
other to ensure that the blood sugar remains in the normal range. In the person without
diabetes, insulin controls the bodys ability to lower the level. The counter
regulatory hormones (e.g., adrenaline, cortisol, growth hormone, and glucagons) control
the bodys ability to raise that level.
Regulation and counter regulation are so finely linked that the blood sugar is always
maintained within normal levels.