Well this is the diet she, and you, will have to deal with for the rest of her life...so basically you can eat what you want ..........But with changes, substitutions !!...no fried constantly, broil or bake...no white potatoes, white breads, rices, pastas..

Learn portion controls, instead of plates of pasta, use dreamfields pasta and make it a side portion with a salad...if you must have bread, use the fiber ones, they are pretty good, I use them and have no major problems - I don't eat more than 2 slices.

No junk food...sodas if you must, diet - coke zero is very good and once you start with these, then you will not have a problem..flavored waters are another but do watch those, I have seen these with carbs from 13 to 30!!!

Learn to count carbs, read labels, watch portion sizes, maybe see if your doctor can recomend a dietician to help....use common sense.
And find her a group such as this so she can talk with others her age.

I have been diabetic for 16 years and pretty much eat what I want, I have always been one for moderation so never run into much problem tho corn sends my numbers sky high so I don't eat it.

Yes I do eat icecream, small cone once in a while, chocoloate, dark kind and have snitched a few french fries from my husband lol... I do a lot of those 100 calory snack packs, watch my carbs, etc and my numbers are in excellent control.

Another thing in the beginning your and her numbers will go all over until in control and the body gets use to the new changes, so don't freak out when you notice this. There is something called the dawn effect and many of use go thru this - morning fasting can be higher than when you went to bed.

Monitor your numbers, test first thing in morning, night and rotate a meal testing 2 hours after eating....and most important get exercise. Being a 12 year old I imagine she might be into sports at school? Do let the school know if this is the case exercise can bring down the numbers very quickly so that needs to be monitored but she can still play sports, there are many athletes out there doing so.

Ask questions

Totally agree with Gayle, get that 12 year old started out right and she will do great for the rest of her life.

Thanks for the advice...we've gotten to the diet soda(I've drank it for years, but she was resisting it--she likes Diet Barq's and she has cut down to maybe 3 cans a week. It is the junk when she is with her friends--she doesn't want me to tell people what she can do, so we are working on selfcontrol. I do tell adults in charge of her issues--that's a safety thing.