Santoshi-
My job is in healthcare and working with people living with diabetes.
I see many of the same challenges for loved ones (spouses, kids etc) of people with DM as I do with those that struggle with addiction. Loved ones CANNOT manage the disease of DM just like we can't manage the disease of addiction (we can try but we all know on this board that only makes us crazy).
Just like there are many ways to manipulate around addiction, there are many ways to manipulate around DM....with or without meds, with or without food management, or activity or stress. There are many types of addiction (especially around food) that come up when living with DM then in the general public. Getting myself help around my own co-dependency has made this job more enjoyable and less caretaking. I hope I am demonstrating for loved ones/patients an appropriate way of being around another's disease. I know I have not always.
My point is this. What you are doing to help yourself around his addiction, might be what you will need to consider doing around his living with diabetes.
Education about the disease can help everyone. I suspect a medical facility near you will have DM education classes/one:one etc, and depending on what you/he decide this might a place to start. Another great place to go is the American Diabetes Association and/or the American Association of Diabetes Educators to start.