Diabetes is quite common in people. It is linked to glucose levels in a person's bloodstream. Usually the level of glucose is quite balanced in a person's blood. The glucose level is controlled by the pancreas. The pancreas secretes insulin regularly into the bloodstream. This keeps the glucose levels constant in the body. The process of respiration happens at the cell level when the bloodstream delivers oxygen, and energy is released. This process normally helps maintain the sugar levels in the blood.
But in some people, the pancreas does not work properly. The levels of insulin drops, and that leads the glucose levels in the bloodstream to rise too high. This can have serious effects for the person: they feel tired and ill. There is a solution: to make artificial insulin which the person injects regularly. This balances the glucose levels in the person's body and means the person feels back to normal.