Thanks for writing in to Healthcare Magic!
You have received the vitamin B12
in view of possibility of deficiency of the vitamin and a neuropathy.
Have you ever done an NCV test, if not get it now.
If she is diabetic then you should control the blood sugar tightly.
One year is a sufficient duration if the problem has not resolved yet then it's high time when you should consult a neurologist
and get a detailed physical examination.
If you have any further query please let me know I would try to answer it for you.
Wish you a great health!