The Pancreas is an organ within the human body. Its primary function is to make the hormone Insulin, which is used by the body to break down carbohydrates and glucose so that the body can use them and give you energy.
People can suffer from an illness called Diabetes. This is when the Pancreas stops working, or doesn't work as well. It causes the body to not break down sugar properly, so people can feel tired because they don't get the energy from their food. It can also cause damage to other organs, like the kidneys. This is because glucose is removed from the body when you go to the toilet to pass urine. All that sugar builds up in the kidneys and stops them working as well as they should.
Depending on what type of diabetes the person has, they may be able to control it simply by changing their diet, maybe also taking tablets. In more serious cases, they may have to have injections of Insulin several times a day to replace what their Pancreas no longer produces.