Isolated facial itching sensation could suggest involvement of the trigeminal nerve (trigeminal neuralgia). I am assuming that she doesn't have any type of itchy rash on the face that accounts for the symptoms. Also, you didn't mention if the sensation was on both sides or just one side. One-sided (unilateral) is more common in trigeminal neuralgia.

Type 2 diabetes can be associated with nerve damage (neuropathy); however, the trigeminal nerve is not a typical area involved in neuropathy. Your sister needs a check with her primary care doctor as a first step. She may very well need a neurologist to help determine the exact cause of her problem and treatment. I hope this helps.

I have the same type of itch on both sides or my face and sometines only on the right side of my face. So, I do know what you are talking about. I ask my personal doctor that same question just last Monday morning but, I got no answer from my doctor at all. In fact she sort of shoved it off and gave me a look like I was crazy or somthing like that well, that is how I interpeted it anyways. What does it mean when you itch on both sides sometimes and only right side at other times?