Tattoo's generally no problem but the foot may not be a great idea as us diabetics often struggle with feet and healing etc. It's your body but I would personally not get one on my foot. Good luck, whatever you decide
I think you will be ok, go to a tattoo parlour that's well established and clean! I've got a tattoo on the bottom of my neck and had no problems with it healing!
Even for non-diabetics, a tattoo on the foot takes longer to heal and is more painful. I had one a long time before my diagnosis and that's what the tattooist warned me about and he was right.
I have a tattoo on my foot and got it done close to when i started having symptoms so my blood sugar levels were properly all over the place and that healed fine so I'm sure u'll be ok like others have said just make sure its some where that has a good reputation and pay attention to the advice they give