I really feel for you about this. I was diagnosed type 1 a few weeks before my 15th Birthday and throughout the rest of my teenage years, in fact until I was about 23, behaved exactly as your daughter is doing. Looking back now I really regret the way I behaved, luckily I never did myself any major harm at the time and have not developed any serious complications YET, but who knows the future damage I may have caused. My Hba1c was regularly in the 10s or 11s and I stopped going to appointments at the hospital as I got fed up of them saying the same thing every time I went as I knew I had no intentions of listening to them!
The trouble is that you can get away with not properly looking after your diabetes with few immediate consequences, ok there's the chance of severe hypo or DKA, but if you can get away without either of these things happening it's easy to feel like you're not doing any major harm. The majority of consequences are all long term and as a teenager it is very difficult to look that far into the future or think 'it won't happen to me'. When I was being lectured I used to jokingly say 'Oh well, who wants to live past 30 anyway, I don't want to get old'. I just turned 30 this year and believe me that attitude has definitely changed!
It all hit home for me when the first sign of eye damage showed up on my retinal screening, along with the fact that I had reached 23 and 30 wasn't seeming so far away anymore, and that I was in a stable relationship so started thinking that I would like to have children one day. Unfortunately you can't force your daughter to take her Diabetes seriously, she needs to realise how important this is for herself. All you can do is try to get her to realise sooner rather than later, would it help for her to meet older diabetics who may have acted the same as her as teenagers and now have complications and regret acting the way they did? I don't mean pensioners, as she will never be able to relate to someone so much older, but it would probably help to meet someone in their late 20s or early 30s. I have been very lucky so far, but I heard only last week of someone aged 37 who has just been registered blind, and a good friend of mine has nerve damage to her feet and has trouble getting around and doing as she wants. Also the sticky post on here about 'diabetes kills', the lady who so badly wanted to help her husband but he just wouldn't help himself and it ended so tragically, that scared the life out of me. It seems a shame to scare your daughter and not something you would really want to do, but it may be the only thing that makes her realise.
Anyway, I hope that I have been of some help and good luck xx