I have a mild fear of needles. Whenever my wife does acupuncture on me, I am quite uneasy in the beginning, looking away but still I end up covered in a bit of sweat till she finishes putting needles on all the points (and sometimes they are properly weird places I wouldn't imagine sticking tiny needle into... doesn't help). Don't monitor the heart rate/pressure but it must jump up significantly
I have a pretty serious fear of needles, to the point that phlebotomists always ask me if I'm going to pass out (to which I always answer, "never have before, but maybe today's the day!")
Once, I had to give my spouse an injection, and I almost passed out and threw up, once when they took the cap off the syringe and accidentally poked themselves in the finger, and then when I actually had to administer the injection.
I know I'd get used to it, but there's a decent chance that if I had to give myself insulin shots, I'd just fucking die.