How do I help my T1D husband with his burn out?

My husband was diagnosed pretty late at 18 but it’s been about 10 years now and he says he is experiencing diabetic burn out. I have tried leading by example and eating healthy and showing discipline with my lifestyle but he doesn’t seem to want to go along with it. I don’t know how else to help him and I care so much for him. All of his family and me are scared that he is taking years off his life. He has insisted that diabetes doesn’t work that way and I’m inclined to believe him more than them, but I still worry about him. His family also blames me for his decline because I have been overweight all my life and they think me responsible for managing his lifestyle. It puts more pressure on me to help him figure out how to be okay with the lifestyle changes he has to make.