I cannot remember a time I was not a diabetic. Diagnosed barely out of diapers, a long, long time ago.
I have not read the thread yet. My thought for whatever it is worth is simple. If we have the training, have the knowledge, you MUST NOT interfere, unless it is immediately life or death. Unless it is you must let us make the mistakes, whatever they might be.
Whatever the issue testing, food, basic stupidity... by that age they are doing the tests, the math, the injections, the boluses you are not doing them, right? You can reward outright and you can and make serious incentives.
But at the end of the day, both the failures, and the successes are ours. With most things we need guidance, intense humor, and a whole lot of honest sincerity. SO depending on the particular issue(s) there are different approaches, different carrots, different sticks.
If the issue were drinking, or sex you would be straight with her, and listening a whole lot right? This is not that different. What you believe behind closed doors, with your husband, your partner, or even here is a different creature than what you say to your daughter. Treat her like an adult that soon she will be.
Shes gonna make severe mistakes with boys, and with her insulin too, unfortunately. She'll learn, and so will you. What do you feel the biggest issue is for you? Is it fear she'll harm herself long term? You afraid she'll massively screw-up coverage and crash? The very best, the most experienced among us cannot guarantee anything... we do what we can, sometimes we fail. We all do sometimes.
The trick is not making it a habit >: >. Your daughter is NOT a diabetic, she is a teen who ALSO happens to have diabetes as well as her other challenges as well. Different creatures.
So give us a better seat at your "table", the cards you are playing with, perhaps we can help?