The pancreas is the organ that is failing . the pancreas provides insulin to the body to break down food, and a person is diabetic if the body cannot produce enough to break down food.

Thats actually not true the pancreas is for filtering out the sugars in your body it helps the kidneys filter toxins out of your body (it can also help break down food but that's not the main purpose) and if a person is a diabetic it won't be able to work with the kidneys to filter out the toxins and sugars. Thats when they have to use the Insulin to help it filter it out. (My mom has diabetes so i know this)