It is quite possible the vaccine will have an effect on Blood sugar. I know for me everything seems to effect blood glucose. I really have to be careful following shots of any kind. One type of shot I would warn all Diabetics to be careful of is Cortisone injections. That type of shot can do a serious number on readings. It makes my reading high all day for several days. I can't take them anymore. I will have my vaccine this Saturday. I will post if I have problems with glucose readings.