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The importance of insulin
You do not need to have diabetes to learn about insulin. Insulin is extremely important to
everyone regardless of your health conditions. When your insulin levels are not balanced, you
can experience low blood sugar episodes, such as headaches after exercising; you can gain much
more weight than you should; you can diet as much as you can and not lose one single pound; and you
can also feel very tired and unable to be productive. All those symptoms can be related to an unbalance
in your insulin levels.
So what is insulin and why it is important?
Inside the pancreas, beta cells make a hormone called insulin. When Food enters the digestive track,
it stimulates the release of insulin from the beta cells. This release depends on the amount and the
type of food eaten. Carbohydrates (sugars and starches) are the most effective stimula?tors.
The combined effects of hormones from the digestive tract and the increasing blood sugar level
sustains the release and formation of insulin.
Like any machine, the body requires materials to make up its structure and replacement materials,
like building materials, to replace those that have worn out. In addition, it needs fuel to provide
energy for it to function. The fuels that the body uses come from the food we eat, which is made
up of carbohydrates (sugars and starches), proteins (amino acids), and fats (fatty acids). Digestion of
the food begins when it arrives in the stomach and is attacked by digestive enzymes. Some of these are
also in the mouth and small intestines. The digestive process is like an assembly line. Foods
carbohydrate, protein, and fat are split apart by enzymes into their basic forms glucose,
amino acid, and fatty acid. Once this process is complete, these basic building blocks of food
pass through the wall of the gut and into the bloodstream to be used for energy. Actually,
all three provide for energy needs, but they must be further broken down or split apart.
This process is known as metabolism. It is like the "burning" of fuel to produce energy.
This energy fuels our activities such as walking, running, or playing sports, as well as the
work of the organs of our body. The waste products of this energy production are carbon dioxide and water.
They are disposed of by way of the kidneys and lungs.
Insulin plays a key role in making sure that our body runs with a full supply of fuel.
Insulin acts like a key that fits into little locks on the surface of the cells. It creates a series of
reactions on the surface of the cell and inside the cell that allows glucose to enter. Without insulin,
the sugar would back up in the blood, unable to get into the cell for use as energy. People with diabetes,
is unable to take the energy or sugar from the blood stream and into the cells. That is why the first
symptom of diabetes is loss of weight, thirst and frequent trips to the restroom. Diabetes is the lack
of enough insulin production in the body to allow the absorption of energy.
Understanding how it all works:
The body uses three main fuels, glucose from carbohydrates, amino acids from proteins,
and fatty acids from fats.
Carbohydrate is found in most foods that are eaten (fruits, vegetables, pastry, bread,
potatoes, etc.) and is frequently called "starch." When these foods are eaten, the carbo?hydrate
is broken apart into simple sugars, and then to basic glucose as it enters the blood circulation.
Once in the blood, glucose travels throughout the body. When it comes in contact with the pancreatic beta
cells, insulin is produced. Pancreas beta cells make and secrete insulin, in response to increased
glucose in the blood. This insulin then travels through the blood? stream as noted earlier, and
attaches itself to each cell surface, telling the cells to allow the glucose to enter the cells to
be used for energy.
Glucose is able to provide energy for immediate needs. As one is eating, however,
the energy requirements are fulfilled. The extra energy must be stored for the future.
There are two places for this energy to be stored: one is the liver, although its storage space
is limited. The other with almost unlimited storage are the fat cells. Insulin helps promote the
change of the excess glucose into fat, which is deposited for long term storage for some people,
longer than others! As a result, there is a myth that insulin injections make you fat.
Insulin doesn't make you fat excess calories make you fat. Insulin only helps by doing its job!
Protein is available from the daily diet (e.g., from meat, cheese, and fish). When such
foods enter the intestine, enzymes break them down into amino acids, which then enter the circulation.
Circulating amino acids can also stimulate the pancreas to secrete insulin. While proteins
contribute to various building components of the body such as muscle and bone and to the production of
enzymes, they are also "burned" to produce energy in a process similar to the metabolism of glucose.
The use of protein as an energy source can occur because amino acids can be changed to glucose in the
liver and then used or stored as glycogen. This glucose can also be changed to fat for storage until needed.
Fat - the third fuel for the human metabolism is found in oils from corn, peanuts, and olives,
as well as fat in meat, butter, and other dairy products such as milk, cream, and cheese.
These foods are digested into fatty acids in the intestine and absorbed into the bloodstream where
they are used by the body. Some fats are called "essential fats." The body needs these for metabolism
and these must be in the diet. Most fats, however, are either used for energy or stored for later use with
the help of insulin. When other fuels are in short supply, such as during prolonged fasting, the level of
insulin in the blood falls. The reduced level of circulating insulin promotes the removal of the fat from the
storage depots and helps its entry into the circulation. It may then, be used by muscle and other organs.
However, fat is metabolized. ("burned") differently than glucose. When it is metabolized, by products may
result because fat is not used as efficiently as other fuels. The remaining byproducts are ketones or acetone.
What Goes Wrong
Diabetes occurs when the blood glucose is too high as a result of a deficiency of available,
effective insulin. This lack can be absolute, when the pancreas does not produce enough insulin
(or produce none at all in case of diabetes type 1) or relative, when the pancreas produces a "normal"
amount of insulin, but for some reason the body needs more than a normal amount of insulin or the insulin
is made ineffective and the pancreas cannot produce enough to compensate. As a result of these deficiencies,
the cells lack fuel, and the body suffers from a lack of energy. People with diabetes complain of weakness
When the cells are starved of their fuel, the body recognizes that not enough food has been eaten
and triggers a sense of extreme hunger. The glucose level in the blood rises because it is not used.
At the same time, out of desperation, the body turns to consume stored fuels such as fat and protein
to try to meet its energy needs. The level of glucose in the blood continues to rise. The huge excess
of unused glucose circulates through the kidney, which normally rescues useful glucose from the filtered
fluid to keep it from being lost in the urine. There is a level of blood glucose, however, known as the
renal threshold, above which the kidneys cannot keep up with the job of retrieving glucose, and it escapes
into the urine. Once this leve is passed, glucose spills into the urine as from an overflowing dam. As the
blood sugar rises, excess glucose appears in the urine. When diabetes is severe, a large proportion of the
body's energy needs are lost into the urine in the form of glucose.
The body knows when the urine is too loaded with sugar and is too concentrated and tries to
dilute it by allowing more and more fluid to flow through the kidneys. Hence, the person with high blood
glucose levels experiences frequent urination of large amounts of fluid. With the fluid loss, the body senses
increasing dehydration, and the thirst center is triggered, making the individ?ual drink more fluid. This vicious
cycle of glucose and water loss, and the attempts to correct this loss, lead to the classic symptoms of diabetes.
All of these are due to the body's inability to use glucose properly as the body fuel.
When a person has the type of diabetes with a severe lack of insulin, this absence allows the
fat cells to release fats, which are converted by the liver into ketones. These ketones are acidic.
If this process proceeds rapidly or for a long enough time, blood ketone levels rise to high levels
and becomes ketoacidosis, which is indeed quite dangerous.
There is also the situation where the body is producing enough insulin but the body for whatever
reason is not properly using that insulin. This can lead to episodes of low blood sugar, which is also
prejudicial to the body. So you need to pay attention on your body and if you experience any of the
symptoms described here, consult your physician for an assesment of your health condition.
Source: Joslin Diabetes Center Manual, Leo Krall and Richard Beaser, 12th Edition.
Adapted by Editorial Staff, January 2008
Last update, August 2008