I have had my navel and both nipples pierced. I am a type 1 diabetic, and it was hard. I eventually ended up taking the piercings out because they just wouldn’t heal. The navel piercing still bled after a year. The nipple piercings healed for the most part, but I had to watch because every time they got infected (and yes I cleaned them regularly) it messed with my BG. I just got tired of dealing with them, but to each her own. If your BGs are good, then carb up a little before you get any body work done (if you don’t you may drop and pass out), and it does have some effect on the healing process, but as long as you take care of yourself any work, be it tattoos or piercings, should be fine.