I had Bells Palsy in my 20's :shock:
It does need to be checked out though to rule out other causes out, I had an emergency out of hours appointment (Sunday) but if you've got a small injury unit near you pop in and have it checked if not ring NHS Direct for further advice.
They will likely do some tests, such as holding arms up, balancing on one leg, a strength of grip on that side, and perhaps a little memory test to rule out stroke side of things, I had this done very scary at the time as I was only 26...
Treatment is generally a course of steriods (you'll have to watch your BG's as steriods can increase them, so might mean adjustments in your diabetic medication) it generally clears with this all be it a slowly, if it doesn't which is rare there is an operation that they can do but as I said this is rare.
The cause is a inflammed and/or blocked nerve in the face (not sure which one though) hence why it's associated with virus/infections but not always it can come out of the blue as mine did..
I didn't have any colds or underlying infections when I had mine, I was pregnant at the time but the night it started I had spent a very uncomfortable night baby sitting for a friend who basically even though it was winter left me with no heating and I was sat in a draft hitting the side I had my bells pusly on...
They will also probably suggest you wear a eye patch, to prevent dust getting in your eyes, which if you are working in a dusty enviornment or even doing house work is advisable because you can't shut your eye... Oh I do suggest if you can wear old tops that you don't mind throwing away, as drinking can be a problem causing a lot of dribbles.. Not pleasent at all and ruins your tops..