It’s called Type 1 Diabetes, or juvenile diabetes.
It does not sound like he has complete pancreatic failure. The pancreas also puts out enzymes that the stomach has to have to process food.
WHile The Juvenile Diabetes Foundation still uses the term, doctors haven’t used the term ‘juvenile’ for a very long time. Insulin dependent diabetes can occur at almost anytime in one’s life-—
The pancreas does not need to completely fail to cause diabetes, only the area called “The Islets of Langerhans”.