I haven't read through all the posts, so these may already have been suggested:
It seems a psychological problem, probably denial as suggested. Have you told him you want the man you married back?
Have you tried both the extreme negatives (what
will happen if he doesn't change and how soon it is likely to happen) and the extreme positives (examples such as those on this forum of people who were very ill managing to turn it around)? If he's in denial then I guess either extremes won't work, but it may be that he responds better to positives than negatives or vice-versa. If you've focused on one in the past, how about focusing on the other.
One thing I think may be very useful for people in denial, or just not taking it seriously enough:
I like that video because it's so matter-of-fact. I don't think your husband will feel either nagged at or encouraged by that video - he'll just see it as an insight into the reality of T2 for people who don't take action. Including one man who's just had a foot removed who warns people to take it seriously.