YANBU. I can't believe some of the attitudes on here.
You could have been desribing my father, down to the loss of ability to walk anywhere and the age of onset. Basically my father was born perfectly healthy but killed himself at the age of 52 due to overeating and lack of exercise. This followed the pattern of diabetes (Type 2 in his case), becoming obese, angina, circulatory problems, high blood pressure, blocked arteries, all sorts of drugs and treatments prescribed, long term absence from work followed by being sacked for unable to work, first heart attack, second heart attack, various heart operations and then the final heart attack which killed him.
He didn't do enough to help himself. He lost a little weight, but was still obese. He did give up smoking, but did not exercise. Basically by the time he was in his early 40s it was too late as he had damaged his body so much.
What concerns me is how his family suffered. My mother shielded me as best she could, but it couldn't disguise the fact that I had to grow up with a father who, due to his own fault, was permanently ill and partially disabled and unwilling unable to do much.
But my mother got incredibly stressed. She had to do everything, and got no help, whilst my father became the centre of attention and got all the help and resources out there. My mother lost a lot of weight, after my father died she recovered but then developed cancer which eventually proved fatal. There is no cancer in our family and she and I often wondered if it was brought on by the years of stress dealing with my father.
Interestingly, I came to the conclusion that my father almost did it deliberately, for attention. He had shown hypochondriac tendencies in the past, even as a young man, and my mother had been going to leave him because he was so lazy. Because he became so ill, she was guilt-tripped into staying with him.
To be honest, having been an observer of this pattern before, I'd advise you to get out now.
btw I doubt going to the GP will encourage your DH to lose weight and take exercise - it has to come from a desire inside himself and it doesn't sound like he has one.
Uncontrolled diabetes is really risky for amputations, and you say your DH's calf is to painful for him to exercise - sounds like severe circulation problems. Is he aware of this?