Ah ha... a classic case of teenage/pre-teenage rebellion... The only reason I can identify it is that I went through it myself, many moons ago (I'm now almost 41). In my ealy teen years, I pretty much denied my diabetes and neglected to take care of myself properly. At the time, I was on MDI, and I would take my insulin before meals, but that was about the extent of my caring for myself. My mindset was always that "I feel okay, so I must be okay". Please don't think that I condone this attitude! Rather, it's more of a confession of something I am not proud of.
My bad attitude lasted for several years. It didn't matter what my parents or my doctors said to me. Then, I paid the price - complications. In 2001, I developed diabetic retinopathy, due to my consistently high BGs for so long. I ended up having four surgeries, not counting the laser surgeries, two in each eye. Following each surgery, I found myself to be blind while I recovered. VERY SCARY, NOT KNOWING IF I WOULD REGAIN MY SIGHT! In the end, I did regain most of my sight, although it is very weakened compared to a non-d person.
Please be assured that I did not tell you all this to scare you. The only advice I could give at this point is to try to find a Type 1 diabetic in your area who has suffered complications. Have a real heart-to-heart with him/her and your daughter. Maybe that'll be enough to get her back on track. Otherwise, I think the comparison could be made to telling a young child: "Don't touch the stove; you'll get burned"... of course, the child has to do the opposite!
All the best of luck to you and to your daughter.