Insulin is normally produced by the body. It is released by the pancreas in response to a meal to signal cells to take up the sugar glucose for energy or storage. In diabetes mellitus, either the body stops producing insulin, or the cells stop responding to it. As a result, the glucose level in the blood is elevated. Short-term high elevations of blood sugar can be fatal. Long-term elevations lead to problems in the organs, especially by damaging blood vessels. Insulin can be given as a medication to help lower blood glucose to a normal range. However, it is important that insulin be administered under the guidance of a health care professional.
Insulin Production
Insulin is a protein hormone produced by the pancreas, a digestive organ located in the center of the abdomen. Specialized cells called beta cells are responsible for this production. These cells store insulin to be released as needed by the body. They detect chemical changes in the body from the intake of food and as a result release insulin into the blood.
Insulin Function
When food enters the body, carbohydrates are broken down and sugar levels in the blood rise, predominantly the blood sugar glucose. In turn, insulin enters the bloodstream, binds to cells throughout the body and signals the body to take up glucose from the blood. Therefore, insulin functions to lower the blood sugar and supply cells with glucose that can be stored or used for energy.
Synthetic Insulin
The insulin protein can be synthesized for medical use. Many insulin medications are not exact copies of insulin. Instead they are slightly chemically modified to act sooner or later and over shorter or longer periods of time. Some insulin medications are designed to be fast acting, with a peak effect in about 15 minutes. Others are long acting, with an effect that is drawn out over 12 or more hours; and others are somewhere in between.
Administration
Insulin is administered under the skin, not by mouth. This is because it is a protein and would be digested if taken into the stomach. A deposit of insulin under the skin allows the insulin to seep into the bloodstream to exert its effects just like naturally produced insulin. In the case of type 1 diabetes mellitus, in which the pancreas fails to produce insulin, synthetic insulin can be administered to take its place. In type 2 diabetes, in which the cells are resistant to insulin, extra levels of synthetic insulin can help overcome the resistance.
References
- "Physiology"; Linda S. Costanzo; 4th Edition; 2008
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci et al.; 17th Edition; 2008
- "Basic and Clinical Pharmacology"; Bertram Katzung et al.; 11th Edition; 2009
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