In my experience it’s not high BGs, per se, that affect sensor life but rather BG variation. My sensors seem to last much longer when I eat low carb and rarely see angled up or down arrows (and basically never see straight up or down or double up or down arrows) than when I’m eating higher carbs and my blood sugar fluctuates more. But that’s just an anecdotal observation.
I would consider my immune system to be quite strong (I get perhaps one cold a year) and quite overactive (two autoimmune diseases, six allergic diseases, many allergies/sensitivities, including being allergic to most infusion sets and tapes). So I’m not sure it’s a matter of immune system strength, although I think immune systems can definitely “take out” sensors and infusion sets (I’ve experienced the latter many times).
I think part of my success in sensor longevity is because I will put up with a lot of itching, irritation, and inaccurate (or no) data before I pull a sensor I paid $85 for. I’ve not uncommonly had a sensor provide no usable data for approaching a week before I finally got it to turn around or give up, and no amount of physical discomfort will cause me to pull a sensor. I don’t know many other people who would put up with that.