The human metabolism is quite complex. Now you have been diagnosed, you will be having regular blood tests. If a combination of stress and your infection was the trigger, as your body recovers and stress declines, you may see your HbA1c falling.
Since you are on a sulfonylurea, assuming you drive, you should have a BG meter. According to DVLA guidelines, you must notify them and you must test your BG levels before you drive. Below 5, don't drive! You may need to be assertive because your doctor may try to fob you off because the strips are not cheap, but NICE guidelines are that you should have a monitor and strips on prescription.
When yo0u start testing, you will start to get an idea of how good your BG control is. Some of the Beta cells in your islets of langerhans will probably have been damaged by the high BG levels, but in time, with good BG control they can recover so there is a chance you may well improve over the longer term. Your doctor will monitor you regularly until you are stable. I would push for three-monthly blood tests to start with and if you start to get hypos, go back and see the doctor.