INSULIN

Insulin is a hormone produced by beta cells in the pancreas. It has three important functions

1.Allow glucose to pass into cells, where it is used for energy.

2. Suppress excess production of sugar in the liver and muscles.

3.Suppress breakdown of fat for energy.

In the absence of insulin, blood sugar levels rise because muscle and fat cells aren't able to utilize glucose for energy. They signal the body that they're "hungry." The liver then releases glycogen, a form of stored glucose. This further increases the blood sugar level. When the blood sugar level reaches about 180 mg/dl, glucose begins to spill into the urine. Large amounts of water are needed to dissolve the excess sugar, resulting in excessive thirst and urination. This condition is called Diabetes mellitus

Without glucose for energy, the body begins to metabolize protein and fat. Fat metabolism results in the production of ketones in the liver. Ketones are excreted in the urine along with sodium bicarbonate, which results in a decrease in the pH of the blood. This condition is called acidosis. To correct the acidosis, the body begins a deep, labored respiration, called Kussmaul's respiration. Left unchecked, a person in this situation will fall into a coma and die.

Production of Insulin in the Body
The creation of insulin in the beta cells of the pancreas is a two step procedure. Beta cells first produce preproinsulin. Preproinsulin is cleaved to create proinsulin, which is further cleaved to produce equal amounts of insulin and C-peptide. Endogenous (self-produced) insulin has a half-life of about four minutes in the bloodstream. C-peptide lasts about 30 minutes. By measuring the amount of C-peptide in the blood, scientists can determine the amount of insulin produced by the pancreas.
In people who do not have diabetes, the pancreas stores about 200 units of insulin. The average basal rate for adults is one to two units per hour. After meals, insulin secretion increases to four-to-six units per hour.

Reason behind injecting insulin to Diabetes patients
Insulin must be injected because it is a protein. If it were taken orally, the body's digestive system would break it down, rendering it useless.

Storing of insulin
Unopened insulin vials should be kept cool. Storing them in the refrigerator will help them last as long as possible. Never freeze insulin, however, as freezing can destroy it. Open insulin, whether vials or pens, can be kept at room temperature for about a month.

Manufacturing of insulin
Insulin used by people with diabetes can come from three sources: human (created via recombinant DNA methods), pork, or beef. Beef insulin has been discontinued, and essentially all people who are newly diagnosed are placed on human insulin.

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