Hello Sir, yes it is normal to experience the problem that you describe. Post-diagnosis as you blood sugars are stabilized, it is normal for glucose to move to the back of your eyes, this distorts the lenses of the eye, this causes you to have problem with reading for a wile.
After my diagnosis, I had this problem very badly, my eyesight was reduced to about 45% of normal, this lasted for three months in my case before I could even drive a car. It will get better, in your case it could be a short term thing or like me it could last longer, there is nothing you can do about it you just have to ride it out.