My diabetic Mother-in-law is living alone with health issues and won't trust doctors' recomendations or treatments. What will it take to get her to accept the help she really needs and start living instead of dying?

My diabetic mother in law is 77 years old living alone. The most serious of her diabetes related symptoms are about 80% vision loss and high blood pressure. Her doctors, daughters, and I believe the most serious threat to her health is depression. She has all the classic symptoms of depression but she rejects the notion comletely, even if her doctors try to suggest the possibility. She has good support from her family for her day to day needs, but is on a path that looks like self-destruction because of her stubbornness. Because of her failing health, she needs to start making changes in her lifestyle that will set herself up for later years. She doesn't want to move out of her house, or let someone else move in or change anything. She just wants her kids to be there for her. Her kids are there for her as much as they can be, but that isn't enough.
What will it take to get her to accept the help she really needs and start living instead of dying?
HELP, Jon