Insulin is a hormone, a chemical that's made in one organ of the body — in this case, the pancreas — and travels throughout the body via the bloodstream performing its task. Insulin's task is to permit the entrance of glucose (the sugar in the blood that provides energy) into the cells of the body, especially muscle and liver cells.
Think of your insulin as an insurance agent who lives in San Francisco (which is your pancreas) but travels from there to do business in Seattle (your muscles), Denver (your fat tissue), Los Angeles (your liver), and other places. This insulin insurance agent is insuring your good health.
Wherever insulin travels in your body, it opens up the cells so that glucose can enter them. After glucose enters them, the cells immediately use it for energy, store it in a storage form of glucose (called glycogen) for rapid use later on, or convert it to fat for use even later as energy.
After glucose leaves your blood and enters your cells, your blood glucose level falls. Your pancreas can tell when your glucose is falling, and it turns off the release of insulin to prevent unhealthy low levels of blood glucose called hypoglycemia (see Chapter 4). At the same time, your liver begins to release glucose from storage and makes new glucose from amino acids in your blood to raise the level again.
If your insurance agent (insulin, remember? — stick with me here!) doesn't show up when you need him (meaning that you have an absence of insulin, as in type 1 diabetes), your insurance coverage may be very poor (in which case your blood glucose starts to climb). In other words, a lack of insulin means that glucose in the blood isn't allowed to enter cells in the body, and the amount of glucose in the blood rises to an unhealthy level. High blood glucose is the beginning of all your problems. (Flip to Chapter 2 for more information about the overall role of insulin in type 1 diabetes.)
If all insulin did was permit glucose to enter cells, that would be enough. But insulin has a number of other actions. These include the following:
il Uptake of amino acids by cells. Amino acids are the building blocks of proteins, and proteins make up muscle.
i Conversion of glucose into glycogen, its storage form in muscle and the liver.
i Synthesis of fat in fat cells, the liver, and muscle for further storage of energy.
i Regulation of the growth of beta cells, in which insulin is made, as well as protection of the beta cells from death.
i Regulation of the release of insulin from the beta cells. It does this by allowing glucose to enter the beta cell, where it stimulates the release of more insulin.
i Synthesis of DNA, the building blocks of chromosomes, which carry genetic material.
Is insulin important? This list of essential actions leaves little doubt about that.
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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...