She lost her husband and mother within a few months of each other My mom was her moms caregiver and she suffered from dementia. In November she moved in with my oldest sister who has health issues herself and is trying to cope with this. She gets up at night and makes all kinds of food and eats like it is going out of style. She hides food in her room. My sister asked her how much she weighed and she said, "That she had not gained any weight." Which is not true, she did not have a big gut when she moved in but now she does. In April she had what was thought of a stroke but her doctor said that it might have been a migraine. She lost her speech and it was days before she regained it back. My sister said that she had another one this week. With the diabetes she does not check her insulin levels. My sister is at a loss as what to do. She does not want to watch her kill herself.
It sounds like your mother actually has an eating disorder caused by stress and depression from the loss in her life of two people she adored. That is one way many people comfort themselves.
Is your mom on insulin? If so, may I suggest that you ask her doctor about continuous glucose monitoring? This device would continuously monitor her levels and administer a bolus of insulin as needed. This would help a lot and keep her covered no matter what she is doing.
Also, she might well need anti-depressants and a good therapist or grief counselor to talk to so she can work through the grief. Perhaps some family can enjoy outings and walks together both for exercise and to release endorphins which are natural mood lifters. Until the grief is addressed and the depression lifted, your mother is likely to go on hurting herself.
I am really sorry to hear that Mother feels she has to hide food in her room or get up at night to eat it. That adds psychological distress to eating issues.
Would Sister's health issues allow her/encourage her to go for walks with Mother? To me, that would be a perfect first step in a healthy direction. Increase exercise first, then focus on healthy eating. Depending on how the diabetes is being managed, the finger pricks for blood sugar monitring might not be as critical. Unlike exercise and eating correctly, they don't improve anything.
Only Mother controls Mother. Sister can encourage and support and suggest, and you can be supportive of Sis and Mom, but ultimately Mother's health is Motehr's busines.