Really dry sore cracks at the corners of my mouth?

About a week ago I noticed my lips were suddenly quite dry, so I bought another lip balm thinking my current one wasn't working, but it didn't make a difference. 2 days ago it moved to both corners of my mouth. They're very sore and it hurts when I open my mouth. I'm diabetic type 1, so I have blood tests quite often to check everything is ok. Last time I checked, I was borderline anemic. I also knew I had a vitamin D deficiency but I'm not sure if it's for anything else. Should I see my doctor or just leave it?