What is Insulin?

Insulin is a hormone produced by our body’s pancreas. Its function is to make the cells in our body absorb glucose from the blood as their source of energy. Without insulin in the blood, the cells cannot absorb glucose and uses fat instead as energy source. Insulin also plays a vital role in amino acid absorption by the cells.

The pancreas which produces insulin is actually part of the digestive system. Its other functions include production of pancreatic digestive juices and other digestive hormones aside from insulin. Protein from the food we eat signals the release of insulin in the blood. In normal conditions, insulin is released in regular, constant proportions to control excess glucose in the blood. When blood glucose falls below a certain level, the cells use the liver’s stored glucose as energy resource.

Insulin’s discovery dates back to 1869, when Paul Langerhans identified clumps of tissues previously not noticed scattered throughout the pancreas. These lumps of cells were later named islets of Langerhans. Edouard Laguesse later suggested that these cells produce secretions crucial to the digestive functions. Archibald, Paul’s son, was instrumental in identifying the role of these secretions. The term insulin was derived from “insula”, the Latin word for island or islets. Diabetes actually results from the damage to the islets of Langerhans.

It was only in 1921 that Canadian surgeon Frederick Banting with the help of medical student Charles Best was able to extract insulin from the pancreas of a dog. However, it was the purified insulin extract from a fetal calf’s pancreas that made patients then suffering from diabetes relieved of its symptoms. This was in January 1922 and in April of that year the renowned drug firm Eli Lilly and Company provided assistance in the mass production of refined animal insulin. It did not take Lilly long to make a breakthrough. In November of 1922, Lilly was able to produce refined insulin in large quantities and soon after commercial sale of insulin began.

From then on, animal insulin was produced for human use. It was only in 1977 that another major breakthrough came with advances in genetic engineering. Genetically-engineered “human” insulin was produced by Herbert Boyer in a laboratory using E.coli. Boyer went into partnership with Eli Lilly and went on to release commercially the first biosynthetic human insulin in 1982 marketed under the brand name Humulin.

Today, insulin widely available is of the “human” variety but animal insulin is still available under special conditions. There are still diabetics who respond well to animal insulin.