If it pumps too much you're dead - which is why I'm considering it life critical.

Not enough is also bad but hopefully they'll notice and can act accordingly - still a threat too though.

It's not that we're all saying this is an unsafe machine, we're saying that a random person DIY'ing and using such a solution is very risky, there's a reason why commercial medical equipment requires rigorous testing/certifications, etc.

Insulin pumps are both.