Insulin

Insulin is secreted by beta cells in the pancreas and can be considered the hormone of life. The main roles of insulin are as follows:

In the skeletal muscle insulin helps the glucose entry into the muscle and its local storing as glycogen, a kind of concentrated syrup of glucose. Glucose that is not used to obtain muscle glycogen is burned out for energy of the highest quality (“green” energy, without high oxygen consumption). In this way the glucose consumption increases and blood glucose level decreases.
In the liver, insulin decreases local glucose production from other substances and stimulates its local store as glycogen, so it is no longer discharged into the bloodstream to increase blood sugar.
In the adipose tissue, insulin stimulates the takeover of blood glucose and local formation of fat. As a consequence, blood lipids decrease and fat cell volume increases by the accumulation of fat. A higher blood lipid level combined with adequate levels of insulin will stimulate adipose tissue expansion and the person gains undesired weight.
Generally, in most cells insulin stimulates amino acids taking from blood and local synthesis of proteins, promoting cell growth and increasing cell life expectancy.
Insulin stimulates the heart oxygen supply, improving the strength and effectiveness of heart contraction. This way, the heart will function better as a blood pump.