Actually no one "invented" insulin, but in 1921 at the University of Toronto, a young Canadian researcher by the name of Frederick Banting along with his research assistant Charles Best were studying the islets of Langerhans in the pancreas of dogs. They eventually isolated insulin and tested it on diabetic dogs, and were successful in lowering the dogs' blood sugar levels. Seeing the potential for a treatment of "Sugar disease" as diabetes was commonly known at that time, researcher John Macleod and chemist James Collip, then began to help prepare insulin for human use. On January 11, 1922, a 14 year old boy by the name of Leonard Thompson, who was dying of diabetes, was given the first human experimental dose of insulin, and it saved his life.
Before that time, someone who developed diabetes had very little options and many lives were cut short far too soon. Insulin therapy rapidly became the life-saving treatment for type 1 diabetics that we know today, helping them to effectively manage their blood sugar levels. In 1923 both Frederick Banting and John Macleod were awarded the Noble Prize, which they richly deserved, because countless lives have been saved as a result of the work of these brilliant men.
Insulin is an anabolic hormone produced by the endocrine islets of Langerhans cells (a.k.a. beta cells, "islet cells") in the pancreas, and is the only hormone which decreases blood glucose levels. Although digestion can be defined in simple terms, its mechanics are very complex, so we are only going to deal with how insulin is used in the body. After your food is digested the carbohydrates are converted into a usable form of energy (glucose), and is absorbed into the bloodstream. Glucose is used by your body as a primary source of energy and it needs to be delivered to the cells of your body, this is where insulin comes in.
Insulin performs the following actions:
• Insulin controls blood sugar (glucose) levels and is secreted by pancreatic cells in response to rising levels of glucose and/or amino acids in the bloodstream.
• Insulin helps move glucose out of the bloodstream and into the interior of the body's cells (muscles and other tissues), where it can be used as nourishment and energy.
• Insulin promotes and regulates the storage of glycogen (the body's stored sugar in the liver).
• Insulin accelerates the oxidation of sugar in cells.
Because diabetics cannot produce insulin on their own (type 1) or do not have the ability to produce sufficient levels of insulin (type 2), glucose levels will continue to increase in their bloodstream (hyperglycemia), and will have damaging effects if not brought under control. Type 2 diabetics can use diabetic medications to help their bodies produce more insulin, as well as maintaining a proper diet to keep their blood glucose levels under control. Unfortunately type 1 diabetics must have insulin directly injected into their bloodstream. Insulin cannot be taken orally because it would be destroyed by the digestive system and therefore must be administered by injection using insulin syringes or through an insulin pump. It should be noted that type 2 diabetics may also require insulin treatments once their pancreas can no longer produce enough of the hormone.