Role of insulin and other hormones in diabetes
Insulin and glucose
Our bodies require energy to function properly and we get that energy from three food groups: protein, fat, and carbohydrates (sugars, starches, and fibers). When the body digests carbohydrates, they are transformed through digestion into a very important source of instant energy, a form of sugar called glucose.1,2
Three forms of simple sugars (also called monosaccharides) are able to enter the bloodstream directly after digestion. These are often broken down from more complex sugars (polysaccharides and disaccharides). These simple sugars include glucose (found in most carbohydrates, including grains and starches), fructose (found in fruits and vegetables), and galactose (found in dairy products and in certain vegetables). The word glucose comes from the Greek word for sweet, and it is the key source of energy for cells in the body. Upon digestion, glucose can be used for instant energy or stored in the form of glycogen when the body’s energy needs are being met.1,2
Hormones and glucose control
Our bodies depend on the action of a number of different hormones, working together in conjunction, to control how we use glucose.
We depend on insulin, a hormone produced in the beta cells of the pancreas (an organ located behind the stomach) to use glucose. Insulin serves as sort of a “gate keeper,” allowing glucose to enter cells where it can be transformed into energy and used to support vital cell functions. Insulin also has other important functions related to the way our body uses glucose.3,4
In addition to insulin, another hormone produced by beta cells called amylin controls how quickly glucose is released into the blood stream after a meal. It does this by slowing emptying of the stomach and increasing the feeling that your stomach is full.
A group of hormones called incretins (this includes the hormone glucagon-like peptide 1 [GLP-1]) are produced by the intestine and stimulate the body to produce insulin after eating. By enhancing the release of insulin, incretins also slow emptying of the stomach, promote the feeling of fullness, and delay release of glucose into the blood stream.
Incretins work to prevent the hormone glucagon from being released by the pancreas. Glucagon, which is made by the alpha cells of the pancreas, is responsible for transforming glycogen stored in the liver and muscles back into glucose to satisfy the body’s energy needs when food isn’t available.4
Type 2 diabetes and loss of glucose control
All of the hormones introduced above normally work together in a balanced fashion to control glucose in the body and supply the body with its energy needs. What happens in type 2 diabetes is that the body loses the ability to use the insulin it produces effectively (this is called “insulin resistance”). In addition to insulin resistance, the body loses the ability to produce insulin. Deficiencies and loss of coordination among the other hormones involved in glucose control also contribute to type 2 diabetes.5
The hormone insulin…directing energy traffic in the body
The human body is a complex system, something like a large, busy city. In a city, businesses and public utilities are linked by roads (and trains and subways, as well). Just as the health and function of the city depends on an orderly and efficient system of traffic and transportation, the health and function of the body depends on an orderly and efficient system for transporting all the substances (nutrients and other vital substances) that our cells and organs require to stay healthy.
For traffic and transportation to run smoothly in a city, there must be a sophisticated traffic system, including signals to keep everything working automatically and a fully developed communication system for locating problems and responding to them. Of course, one of the most important parts of this system is the traffic cop, who travels from headquarters to problem areas and comes up with solutions to keep traffic flowing.
Think of the blood vessels of the body as the system of streets (and trains and subways) in a city and the city traffic as all of the substances (cells, nutrients, and chemicals) that use this transportation system to get to their destinations: cells, tissues, and organs. Just as in the city, the body’s transportation system needs a sophisticated system of signaling and communication, as well as boots on the street to take care of problems and to make sure that traffic gets to its destination.
Key functions of insulin in the body
Enter the body’s traffic patrol officer: insulin
Insulin is one of the true heroes of the body, a kind of super traffic cop. It doesn’t have the flashy job of chasing down criminals (like the officers in the immune system), but it is in charge of making sure energy traffic (in the form of glucose) flows smoothly and arrives at its cellular destinations. To achieve this, insulin combines almost all of the functions of a well constructed traffic system: it goes to specific locations to facilitate the transport of glucose, it monitors the glucose needs of the body and sends signals to organs and tissues to store glucose as needed, it monitors blood glucose and communicates with the liver to control glucose production, and it can even instruct the body to grow fat and muscle tissue as needed.4
Allows glucose entry into cells. Insulin travels from headquarters (the pancreas, where it is produced) via the bloodstream to individual tissues and cells where it unlocks the gates so that glucose can enter and supply energy.
Stimulates glucose storage. If the energy needs of cells are being met, insulin communicates that to muscle and liver cells and stimulates them to store excess glucose in the form of glycogen, which can later be transformed back into glucose and used for energy when the body needs it.
Regulates blood sugar levels. Insulin also has a key role in regulating blood sugar. If it detects that there is excess glucose in the bloodstream, it can stimulate the liver to stop the chemical reactions that produce glucose.
Stimulates growth of fat and muscle. Not only does insulin help conduct the flow of glucose traffic, it also knows when there is need for fat and muscle and as a “builder hormone” stimulates growth of these tissues.