Insulin - The Hormone You Need
Insulin
The human body needs that its blood glucose (blood sugar) levels be maintained in a very narrow range. Insulin and Glucagon are the hormones that make this happen. Both Insulin and Glucagon are secreted from the pancreas, and thus are referred to as pancreatic endocrine hormones.
Insulin is normally secreted by the beta cells (a type of islet cells) of the pancreas.
The stimulus for Insulin secretion is a HIGH blood glucose...although there is always a low level of Insulin secreted by the pancreas, the amount secreted into the blood increases as the blood glucose rises. Similarly, as blood glucose falls, the amount of Insulin secreted by the pancreatic islets goes down. Insulin has an effect on a number of cells, including muscle, red blood cells, and fat cells. In response to Insulin, these cells absorb glucose out of the blood, the net effect being the lowering of the high blood glucose levels into the normal range.
In people with Type 1 Diabetes, the pancreas no longer makes Insulin, as the beta cells in the body have been destroyed by the body's own immune system (a condition known as an auto-immune disorder). They need Insulin injections to use the glucose from meals for growth and energy.
Initially all patients with Type I Diabetes and a few with Type II diabetes need Insulin. Many people with Type II diabetes may eventually need Insulin. Insulin cannot be taken as a pill. It would be broken down during digestion just like the protein in food. So far, Insulin is only available as an injection.
Types of Insulin
There are several different types of Insulin. They differ according to how they are made, how they work in the body, and how they are priced. Insulin comes from animals (pigs or cows) or is manufactured in labs to be identical to human Insulin. The types are -
- Ultra-short acting Insulin (an example is Lysine-proline analog Insulin, also called Lisproâ or Humalogâ insulin) This Insulin is only available on prescription, though most of the other Insulins can be obtained without prescriptions.
- Short acting Insulin (an example is Regular insulin or Humalinâ R)
- Intermediate-acting Insulin (examples are NPH and Lenteâ or Humalin âN Insulin)
- Long acting Insulin (an example is Ultralenteâ Insulin or Humalinâ U)
- Mixed Insulins (mixtures of NPH and Regular Insulin; examples are 70/30 and 50/50)
- New Mixture- Humalog 75/25 - N/Humalog
- Buffered Insulin (which is used in Insulin pumps)
These types of Insulin are not alike in terms of when and how long they act in the body. 'Onset' is how long the Insulin takes to begin working. 'Peak' is the time when the insulin works the best or most. 'Duration' is how long the insulin keeps working. Onset, peak, and duration for each type of insulin are shown in the following table.
Activity of Different Types of Insulin
The doctor will prescribe the type of insulin that is best for the patient based
on how difficult it is to control the blood sugars as well as on other factors.
It should be noted that ultra-short acting insulin is not approved for use during
pregnancy.
Administration Of Insulin
Insulin shots can be administered by several techniques. The first is the traditional
syringe, or needle. The second is a special insulin pen, a device in which a
cartridge of insulin is put into a pen like syringe. This can be used more than
once. There are also pens with a single dose of insulin that you throw away
after use. The third is a pump the size of a beeper that injects the right amount
of insulin automatically into the bloodstream. The pump is used by people with
more brittle diabetes, or by those who require very tight control of their diabetes
and more control over their lives.
Important Considerations When Using Insulin
Using insulin is not difficult to learn. Usually, a doctor, pharmacist, nurse, or diabetes educator can provide this training. Insulin comes in different strengths. Most manufacturers recommend that insulin be stored in the refrigerator (not the freezer!) when not in use. Insulin should not be used after the expiration date shown on the package. It is also important to learn to recognize the normal appearance of insulin. Regular insulin should be clear. NPHâ, Lenteâ, and Ultralenteâinsulin should be cloudy. But no type of insulin should have any little specks (called precipitates) floating in it. If the insulin doesn't look right, it should not be used.
Most important of all is that the patient uses the insulin exactly as directed by the doctor. Insulin has a very strong effect on blood sugar. Taking the wrong type of insulin or the wrong dose of insulin can have serious results. Insulin should not be mixed unless the patient has been instructed to do so.
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