Hi, this happened to me so don't panic - although the diabetic nurses don't mention it, or warn you, it seems quite common.
I don't know how high your bloods have been and for how long, but when I dropped from in the 20s to normal levels with insulin, within a week, I went from a bit blurry reading, to not being able to see anything, and was signed off work for a month. My HbA1c was 129.5, so I had a long way to come down, after a long time at very high levels, so you may not get such a drastic reaction, fingers crossed.
You may be able to cancel your glasses or get some advice from the optician, as I was told not to order any new ones until I had been stable for a couple months (I was sent to Specsavers by the doctor at that time as he had no idea what to do either!). My eyesight was pretty much back to normal within 6 weeks.
But please don't drive! It took me a bit longer to drive in the dark after I could see the TV, read and use my computer/phone again.
I hope you don't have such a bad reaction, but it was alright in the end
