How to handle my mother, she's very depressed and crying?

You have on her profile that she suffers from depression and anxiety so I am assuming she is on medication for this? If so, maybe its time for adjustments or new meds. Diabetes is manageable. Is she overweight? Then maybe she should lose some weight, it may help her numbers. Cutting out sugars and carbs is a good start. I just read that sugars are not good for depression. Carbs turn to sugar in you body.

https://www.healthline.com/health/depression/sugar-and-depression

Call your Moms diabetic doctor. Ask if he has any training programs and diet for Mom. Some hospital give training. Explain that she is crying all the time.

There must be support groups or options available. Check into that for her. There is probably online support as well. Check the diabetes association website. Check into an antidepressant with her doctor. Check into exercise programs, physical therapy, etc...

And make sure she has POA's in place should the need arise.