My mother was hospitalized last week for not taking her insulin for several months. She was then moved to a mental health facility by the hospital. She was there for two days and the therapist I talked to said she was being tested and observed. Unfortunately, she signed herself out yesterday. I believe she is still a danger to herself because she refuses to take care of herself, is a hoarder, and drives with very poor vision due to the diabities neglect. Is there anything else that I can do to force her to get help? I really feel that if she does not get help she will be found dead.

Can you get her car keys away from her?

Depends some on the state ( if in the US)
In GA, it takes several family members to file in court to have to held for up to three days for required testing ( or her doctor having her committed to be observed)

But beyond three days there has to be serious issues found that could not be dealt with in outpatient, also there has to be funding available to pay the bills for this treatment. Most insurance has very limited coverage.