The pancreatic hormone insulin regulates the amount of sugar, or glucose, in the blood. The hormone glucagon also plays an important role. Together, insulin and glucagon help to maintain blood sugar homeostasis, keeping blood sugar at a stable level. Insulin helps to bring blood sugar levels back down to normal after you eat a meal. Insulin and glucagon are both proteins composed of amino acids.
A Brief History of Insulin
Canadian physician Frederick Banting is credited as discovering insulin. Banting's research, based on Oskar Minkowski's earlier experiments removing the pancreases of dogs, continued into the early 1920s. The removal of the pancreas caused canine diabetes. In 1922, Banting and his colleagues John Macleod, Charles Best and Bertram Collip were able to isolate a hormonal extract from a pancreas. They began treating two children, Leonard Thompson and Elizabeth Hughs, both diabetics. These children became well again after being given the insulin. As a result of their research, Banting and Macleod got the Nobel Prize for physiology/medicine in 1923.
How Blood Sugar Is Maintained
When blood glucose levels rise above normal levels in the body, above about 90 mg/100 ml, insulin brings down blood sugar. When the pancreas releases insulin, glucose goes into cells where it is needed. This causes blood sugar to go back down as the glucose leaves the blood. When blood sugar drops below 90 mg/100 ml, the pancreas releases the hormone glucagon, which causes glycogen, stored in the liver, to be broken down into glucose and released into the blood. When this happens, blood sugar levels begin to rise again.
Physiological Importance of Insulin
Insulin is important to the body because it helps provide readily available energy and allows energy to be stored as fat. This occurs when insulin removes glucose from blood, sending it to cells.Insulin is also needed to form protein. Without insulin, your body burns fat for energy, which creates a state known as ketoacidosis. In this condition, fatty acids called ketones move into the bloodstream. If severe, ketoacidosis can be fatal.
Conditions of Insulin Imbalance
Diabetes mellitus, or type 1, is the most common form of insulin imbalance and causes blood sugar to be too high. In type 1 diabetes, the pancreas does not produce insulin and therefore, insulin is given daily. In type 2 diabetes, the pancreas either does not produce insulin, or the body does not respond well to insulin. Insulin resistance is the inability to use insulin. Type 2 diabetes usually occurs later in life and is treated with dietary control and medication.
References
- "Anatomy and Physiology"; Elaine N. Marieb, R. N., Ph. D., and Katja Hoehn, M. D., Ph. D.; 2008
- Joslin Diabetes Center: Diabetes Information: Diabetes Resource: Managing Diabetes: The History of Insulin
- Nobelprize.org: Educational: The Discovery of Insulin
- Mayo Clinic: Diabetes
