Insulin is a hormone produced by the pancreas. Insulin is responsible for the metabolism of fats and carbohydrates. After we eat our blood sugar levels go up. This is when insulin is released into the blood. The insulin causes the liver and muscles to store the blood sugar (glucose) as glycogen, and as triglycerides in fat cells. This is simply how your body stores energy.
When you are hungry, exercising or haven’t eaten in a while your blood sugars will drop. That is when the stored glucose and triglycerides will be released into the blood to bring the blood sugar levels back up.
People with type 1 & 2 diabetes have a malfunction in the way their bodies respond to insulin. People with type 1 diabetes are usually born with it. In this case the pancreas is incapable of producing insulin, and it has to be injected. Without insulin blood sugar levels can get to toxic level which can be very damaging to the body. Type 2 diabetes is a condition where insulin is present, but the body is resistant to it. In this case medication is often needed to regulate blood sugar levels, and sometimes insulin injections are needed.