Causes and treatment of hair loss?

I know my sister is under immense stress daily, she has awful neuropathy in both legs and feet. It's just heartbreaking. (From diabetes). Her hair has been thinning and she said clumps come out after washing it. She showed me and it's a LOT now that comes out.
She said it's not growing back. I'm sure it's stress plus the effects of unstable diabetes perhaps.

Any treatment ideas?