Blurred vision is normal after bringing down blood sugars.
This was explained to me that sugary tears have a different focal length to salty tears and our lens change shape to account for this. When our blood sugars are high, our bodies look for ways to get rid of the excess sugar. This is why we pee a lot, why dentists may be able to detect diabetes and sugar comes out through our tears.
As with everything diabetes, the length of time it takes for our eyes to adjust back to salty tears differs from person to person. Typically, it returns within a week or two but others find it takes longer and benefit from buying a pair of cheap ready readers. But don't waste your money going to the opticians and buying expensive prescription glasses.