Should my wife go to the er for her 250+ blood sugar level?

My wife went to the ER on wed and they said she had the start of Ammonia and Bronchitis. They gave her some medication and one was prednisone. Most of the time her blood sugar is only like 115 to 129 but today at 5pm was 139 7pm 189 10pm 201 1230am 253... it just keeps going up. Wed night it was in the 300's. i haven't checked it since 1230 since she is in bed now. I called her sugar doctor but they called back late and when he tried to call them back there office was closed for the day. Most likely we will call again in am but they are not good at getting back quick. Should she just go back o er or is the prednisone just making it go up and she will be OK. I do know 250+ is high but i don't want the er to laugh at her when she goes in and say just go home.