Insulin is a hormone made by the pancreas in the body that controls the glucose level in the blood.
Insulin promotes the absorption of sugar from the blood. The sugar is stored as fat cells. People who cannot make insulin in their bodies, or enough for their needs, have the disease diabetes.
When blood glucose levels fall below a certain level, the human body begins to use stored sugar as an energy source through glycogenolysis. This process breaks down the glycogen stored in the liver and muscles into glucose which can then be used as an energy source. Insulin is a central metabolic control mechanism. Insulin is also used as a control signal to other body systems (such as amino acid uptake by body cells). In addition, it has several other anabolic effects throughout the body.
Human insulin is a peptide hormone composed of 51 amino acids and has a molecular weight of 5808 Da. The islets of Langerhans in the pancreas produces insulin. The name comes from the Latin insula for "island". Insulin's structure varies slightly between species of animals. Porcine insulin is especially close to the human version. So, people with diabetes can take in insulin got from pigs instead of producing their own insulin.