Leonard Thompson (17 July 1908-20 April 1935) was the first person to have received an injection of insulin as a treatment for type 1 diabetes.
Thompson was first treated at the Hospital for Sick Children before being transferred to the care of physicians Andrew Almon Fletcher, Duncan Archibald Graham, and Walter Ruggles Campbell.
Thompson received his first injection in Toronto, Ontario, on 11 January 1922, at 13 years of age. The first injection had an apparent impurity which was the likely cause for the allergic reaction he displayed. After a refined process was developed by James Collip to improve the canine pancreas extract, the second dosage was successfully delivered to the young patient 12 days after the first.
Thompson showed signs of improved health and went on to live 13 more years taking doses of insulin, before dying of pneumonia at age 26.
Until insulin was made clinically available, a diagnosis of type 1 diabetes was a death sentence, more or less quickly (usually within months, and frequently within weeks or days).
Insulin (from Latin insula, island) is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (INS) gene. It is the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into cells of the liver, fat, and skeletal muscles. In these tissues the absorbed glucose is converted into either glycogen, via glycogenesis, or fats (triglycerides), via lipogenesis; in the liver, glucose is converted into both.
Glucose production and secretion by the liver are strongly inhibited by high concentrations of insulin in the blood. Circulating insulin also affects the synthesis of proteins in a wide variety of tissues. It is thus an anabolic hormone, promoting the conversion of small molecules in the blood into large molecules in the cells. Low insulin in the blood has the opposite effect, promoting widespread catabolism, especially of reserve body fat.
Beta cells are sensitive to blood sugar levels so that they secrete insulin into the blood in response to high level of glucose, and inhibit secretion of insulin when glucose levels are low.
Insulin production is also regulated by glucose: high glucose promotes insulin production while low glucose levels lead to lower production.
Insulin enhances glucose uptake and metabolism in the cells, thereby reducing blood sugar. Their neighbouring alpha cells, by taking their cues from the beta cells, secrete glucagon into the blood in the opposite manner: increased secretion when blood glucose is low, and decreased secretion when glucose concentrations are high. Glucagon increases blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver.
The secretion of insulin and glucagon into the blood in response to the blood glucose concentration is the primary mechanism of glucose homeostasis.
Decreased or absent insulin activity results in diabetes, a condition of high blood sugar level (hyperglycaemia). There are two types of the disease. In type 1 diabetes, the beta cells are destroyed by an autoimmune reaction so that insulin can no longer be synthesized or be secreted into the blood.
In type 2 diabetes, the destruction of beta cells is less pronounced than in type 1, and is not due to an autoimmune process. Instead, there is an accumulation of amyloid in the pancreatic islets, which likely disrupts their anatomy and physiology.
The pathogenesis of type 2 diabetes is not well understood but reduced population of islet beta-cells, reduced secretory function of islet beta-cells that survive, and peripheral tissue insulin resistance are known to be involved. Type 2 diabetes is characterized by increased glucagon secretion which is unaffected by, and unresponsive to the concentration of blood glucose. But insulin is still secreted into the blood in response to the blood glucose. As a result, glucose accumulates in the blood.
The human insulin protein is composed of 51 amino acids, and has a molecular mass of 5808 Da. It is a heterodimer of an A-chain and a B-chain, which are linked together by disulfide bonds. Insulin's structure varies slightly between species of animals. Insulin from non-human animal sources differs somewhat in effectiveness (in carbohydrate metabolism effects) from human insulin because of these variations. Porcine insulin is especially close to the human version, and was widely used to treat type 1 diabetics before human insulin could be produced in large quantities by recombinant DNA technologies.
Insulin was the first peptide hormone discovered.
Frederick Banting and Charles Best, working in the laboratory of John Macleod at the University of Toronto, were the first to isolate insulin from dog pancreas in 1921. Frederick Sanger sequenced the amino acid structure in 1951, which made insulin the first protein to be fully sequenced. The crystal structure of insulin in the solid state was determined by Dorothy Hodgkin in 1969. Insulin is also the first protein to be chemically synthesised and produced by DNA recombinant technology. It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.
More information: University of Toronto
It enables the diabetic to burn sufficient carbohydrates
so that proteins and fats may be added to the diet
in sufficient quantities to provide energy
for the economic burdens of life.
Frederick Banting
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