post prandial value on a single day  tells that the  sugars are normal on that day It doesn't tell about sugar control in the whole pregnancy till term If you switch to normal diet ,sugars may start increasing and is not good  for the baby You need to monitor sugars twice weekly throughout pregnancy and adjust diet accordingly (add few things if sugars r normal) After delivery, u can have normal diet and check for HBA1C at 6 weeks postpartum