Insulin pumps are worn externally with a catheter subcutaneously attached to the body. A pacemaker is internal and would not be noticed by security.
My wife had a kindle fried by a security machine at Munich. Amazon guesses it was static electricity built up by the conveyor and not the x-rays themselves. I suppose this is a danger for machines like an IPump - you don't want to fry the processor which could lead to no insulin (bad) or unregulated amounts (even worse).
I'm about to experiment with a continuous glucose monitor which is attached to the body in a similar way. I can hardly wait to go through security.