Insulin – Function and Importance

Insulin was the first hormone identified in 1920s, which won the doctor and medical student who discovered it the Nobel Prize (Banting and Best).


Insulin is a hormone produced by the pancreas that regulates the level of glucose, a simple sugar that provides energy, in the blood. The human body requires a steady amount of glucose throughout the day and that glucose comes from the foods that we eat.


The pancreas lies at the back of the abdomen behind the stomach and has two main functions:

To produce juices that flow into the digestive system to help us digest food

To produce the hormone called insulin. 


Insulin is the key hormone that controls the flow of glucose (sugar) in and out of the cells of the body. Carbohydrates (or sugars) are absorbed from the intestines into the bloodstream after a meal. Insulin is then secreted by the pancreas in response to this detected increase in blood sugar. Most cells of the body have insulin receptors which bind the insulin which is in the circulation.  When a cell has insulin attached to its surface, the cell activates other receptors designed to absorb glucose (sugar) from the blood stream into the inside of the cell.


The role of insulin can be categorised as follows:


Insulin is central to regulating carbohydrate and fat metabolism in the body

Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle

Insulin stops the use of fat as an energy source by inhibiting the release of glucagon

As its level is a central metabolic control mechanism, its status is also used as a control signal to other body systems (such as amino acid uptake by body cells

Insulin also influences other body functions, such as vascular compliance and cognition. Once insulin enters the human brain, it enhances learning and memory and in particular benefits verbal memory.