Susan,My heart goes out to you. I wish I had some "magic" answers that would help you with your husband.
I am the wife of a Type II diabetic. My husband's grandmother and mother were diabetics. Both did do what they should have done. I won't bore you with family histry but let's just say heritey plays a "big" part. Lifestyle also plays a "big" part. Our of five children on my husbands side, so far he is the only diabetic.
I worry about my two daughters and my 5 grandchilden.
You need to direct your energy to those teens you have. Educate yourself. Educate them. You have access to the web. Cook healthy. Teen's can have a bottom pit! (I raised two) Work with them, if at all possible. You have control with the kind of food that's in the house and you cook. (No?)
Just doing that will not only help you and your children but your husband. (Watch the portion sizes for all and only cook so much for all.) You care and I know you can do it.
Living a "hair" differently and having more support from those teens (it is their future too) of yours might help not only, you but your husband.
My heart and prayers are with you each and every day.
Gail