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The word insulin is derived from the Latin “insula” which means island. Insulin is a hormone produced by the pancreas, specifically by beta cells in the Langerhans Islands.
Insulin regulates the metabolism of carbohydrates, proteins, and fats. This hormone was discovered by Fredrick Grant Banting and John James Rickard McLeod, who were awarded the Nobel Prize in Medicine and Physiology in 1923.
Previously, in 1869, Paul Langerhans defined the islands of the pancreas that were later named after him. In 1889 Josef von Mering and Oskar Minkowski discovered that without pancreas, dogs developed diabetes. And in 1916, Nicolae Constantin Paulescu, professor of physiology at the Bucharest University of Medicine and Pharmacy, was the first to isolate insulin, which he called pancrein.
In 1921, two Toronto doctors repeated Von Mering and Minkowski's experiment by removing the pancreas from dogs and found that insulin deficiency caused increased blood glucose levels. Interestingly, if they were injected with pancreas extract, their glucose levels decreased.
These experiments indicate that a molecule in the pancreas could control glucose levels. A year later, a diabetic boy was given insulin. Until then, type 1 diabetes (in which the beta cells of the pancreas are destroyed by an autoimmune disease) was considered a fatal disease.
We now know that the cells of the pancreas respond to the dietary intake of sugar and release insulin into the circulatory system and can act on liver, muscle, and fat cells (adipocytes). When insulin binds to its receptor on these cells, glucose enters the cells.
The cells use glucose as a source of energy but also store it as in the case of the liver and muscle.
Blood glucose levels remain normal even during fasting because the liver releases stored glucose through a process called glycogenesis. Glycogenesis is regulated by two hormones, one is insulin that inhibits it, and glucagon that stimulates it.
The liver can produce up to 250 grams of glucose a day. In diabetics, the liver can produce up to 500 grams of glucose per day which explains why patients can have high blood glucose levels regardless of food intake.
Insulin is the only hormone that promotes the accumulation of fat stores in adipose tissue and supports the retention of stored fat. The complete lack of insulin leads to fat loss.
Before developing diabetes, insulin levels increase to compensate for the excess glucose in the blood but if the level of insulin in the blood is high, the density of the receptors decreases (downregulation) so resistance to insulin.
In type 2 diabetes, associated with metabolic syndrome and caused by poor eating habits among other factors, the initial treatment is not insulin, but with changes in lifestyle, weight loss and antidiabetic drugs in tablets. However, once the disease has progressed and beta cell depletion begins, insulin must be administered.
The administration of insulin is subcutaneous, in the arms, legs or abdomen. There are small syringes and very fine needles designed to administer insulin.
Insulin cannot be taken in tablets because it breaks down in the stomach. Researchers are testing options like intranasal insulin.
Insulin injection should be administered 15-20 minutes before or immediately after a meal, reaches its maximum effect in 2-4 hours and can last up to 6-8 hours.
There is an ultra-fast-acting version of insulin that you can eat right away. The duration of action of intermediate-acting insulin is 6-10 hours, this type of insulin can be taken in the morning to cover the first half of the day or in the afternoon to cover the nights. Finally, long-acting insulin has an effect for the first 6 hours but covers the next 28-36 hours.
Hypoglycemia (low glucose levels) is a side effect of insulin treatment. Long-term use of insulin can also cause skin damage due to injections and accumulate fat in that area, so it is advisable to change the injection site.
Insulin is a great discovery that has saved millions of lives.
Acknowledgement to Dezső Sándor for compiling information