My daughter is 15 and I am her primary carer, she has lovely long thick blond hair and ever since she got diagnosed 3 months ago she has also suffered with hair loss. She has been checked for thyroid but the result came back ok. I asked our diabetic support nurse and she said it's a result of high Blood sugar and once it was under control the hair loss would stop. This can take up to 6 months but I think it is starting to get better now as I don't seem to be collecting as many hairs.
I hope this is helpful to you. Also take a vitamin D to boost it.