just a thought -- could it be you are too near your ribs and it is breathing that stretches causing you the discomfortI am on Medtronic 640G and am using Mio sets (6mm) which seem to be really comfy but I've noticed if I insert them a little too high on waist (nearer ribs) it is a little uncomfortable (feels like it's pinching). Think the area doesn't have enough fat and its hitting muscle.