A type 1 diabetic may sometimes think their pancreas is useless, since it no longer produces insulin, but the pancreas has other important functions. It produces enzymes that help the body to digest fats, carbohydrates, and proteins. A type 1 diabetic's pancreas may not produce insulin, but it can still produce those enzymes. That is why I do not consider my pancreas to be useless.
My father-in-law was diagnosed with pancreatic cancer, and his pancreas was removed. He had to inject insulin for the rest of his life. He was also given pills that served the purpose of the missing enzymes.