I'm also 29, I'm no longer a type 1 diabetic, as I had a pancreas transplant on the 02/01/08!!
I did have type 1 diabetes for 20 years, I was diagnosed when I was nine, I was very uncontrolled as I used to withold my insulin to lose weight (often known unofficially as Diabulimia) I had my tattoo at 17, and had no problems what so ever with it. Although, these days I would advise a little more caution than I used back then. Make sure your glucose levels are under control, the tattooist you choose is reputable and make sure you clean and take care of it as advised.
Good Luck!!