What it is and how it works
Insulin is a hormone in the body that is produced by an organ called the Pancreas. Insulin is necessary to ensure the metabolism of carbohydrates, fats and amino acids occurs properly with the body, and without insulin, we cannot survive.
Important stuff to know
You may have heard about the "building blocks" of proteins: amino acids. Insulin molecules
are made up of 2 chains of amino acids, 51 in all, arranged in a very specific order.
The 2 chains are attached to each other in a very specific way, and as a result, the insulin
molecule has a very special and definite shape. This shape allows the insulin to act in the body
the way it does.
Important to know: if insulin loses its shape, it will no longer work.
This is important to remember when you consider how best to use and store insulin that is injected.
How is Insulin made in the body?
Insulin is produced by certain cells in the Pancreas. A small part of the Pancreas is known
as the "Islets of Langerhans", and within this area we find the beta cells that make and release insulin.
How is Insulin released?
Generally, insulin is released by the beta cells in two ways:
Rapid, or fast release, of insulin
This is in response to something that triggers this release. The main cause of this fast release of insulin is a rise in blood glucose.
Blood glucose rises most commonly after you have eaten a meal. The high blood glucose triggers the release of insulin, which then causes the glucose to be moved out of the blood into the cells of the body.
There are some other causes for a fast release of insulin. These include various medications (including diabetes medications), as well as another group of hormones, called the "incretin" hormones. These hormones are released by the gut, in response to eating.
Sustained, or slow release of insulin
This does not depend on anything to trigger the release. Insulin is continuously released into the blood from the beta cells.
This insulin level in the blood is known as the background, or basal level of insulin. There should always be a basal level of insulin available in the blood and this slow release of insulin ensures that this is the case.
How does insulin work in the body?
Insulin does many things in the body. The main actions of insulin include:
Controlling the way glucose is moved into cells and how glucose is used in the cells
Controlling the way fats are moved into cells and how fats are used in the cells
Controlling the way amino acids are moved into cells and how amino acids are used in the cells
Converting glucose into glycogen, which is the "storage" form of glucose
Without enough insulin, these actions cannot happen properly, with the result that glucose and fat levels in the blood are not maintained at the correct levels.
Insulin levels in the body are never constant, and they vary, according to a number of factors.
The main influence on insulin levels is the level of glucose in the blood. Insulin levels and the release of insulin usually matches the blood glucose levels.
At meal times, when we eat, blood glucose levels rise, and very shortly thereafter, insulin levels rise.
However there are other factors that influence insulin levels as well. These include exercise, stress, illness, as well as the different types of food and carbohydrate eaten.