I have one tattoo that I got after about 15 years of being diabetic. To be honest, I don't remember diabetes being a consideration (though I assumed I might heal a bit more slowly). I followed directions for care afterward because I like my tattoo and want it to look its best for as long as possible. I'm glad no one told me I couldn't get a tattoo just because I have diabetes!
My tattoo is pretty small. After reading that article, it occurs to me that I should be more careful about my blood sugar prep beforehand in case my next tattoo takes longer - going too low or too high during the application would bite!