I too experienced this with menopause, I don’t think it was down to my diabetes because my hair didn’t change in the first 6 years of my T2 until I hit the menopause, I now take collagen, biotin, B12, & folic acid (you need folic acid for the biotin & collagen to work) and my hair has thickened a bit and I have baby hairs around my temple. Don’t expect results over night, it takes about 4-6 months to see changes but I’m 2 years in and I have really good results now.
I always had very fine hair but lots of it, haven’t got as much as I used to have but it’s definitely improved