Hi Nanaclaire, sounds like you’re maybe in a vicious circle of high blood sugars making you prone to infection, then infection causing high blood sugars. Apart from Metformin, what other things are you doing to help your Diabetes? What type of diet do you eat and do you exercise at all?
I take a daily dose of Vitamin C and zinc, I have done for several years from before my type 2 diagnosis as I was fed up of spending winter time with a constant succession of colds, I rarely get one now.
EDIT Just realised you’re type 1, so I probably won’t be able to help but I’m sure some Type 1s will come along to assist you.