I'm sure you know this, but giving someone a large and unexpected bolus of insulin is a good way to kill them, particularly if they are asleep.

If I were designing an artificial electronic pancreas like that, I would be super, super paranoid. It's probably one of the few medical devices that I really think should be a strong user of asymmetric cryptography with a challenge-response-challenge-response protocol and multiple independent sanity-checking validation steps at every opportunity. If it can't deliver the bolus it thinks you need, it should alarm loudly and tell you to manually check. If it has a bit flip in the night and slowly drives 255 units of insulin into your bloodstream at 3 am, you won't wake up.