I have two, and they healed fine, but then I do have good luck healing without scars. Tattoos normally take about three weeks to heal fully if I strictly follow aftercare instructions. I recommend using H2Ocean for tattoo and piercing aftercare; it reduced pain and inflammation and seemed to speed healing for my 2nd tattoo. If it were me, I think I'd go for a small, simple one the first time and make sure there aren't scars that distort the image. Sounds like diabetes shouldn't affect it, but your normal healing and scarring may. But a tattoo isn't exactly like a cut that opens and bleeds - it's more like a scratch in terms of the actual wound and scab created. Or rather, a lot of scratches. So if you follow the aftercare rules and are very careful to let it take its sweet time to heal, I'm guessing it'll be fine. Let us know what you decide and how it goes if you get one, okay? Out of curiosity, what design are you thinking of?