The most common reason for such swings in glucose
scores is because of residue on your fingers when you test
. Make sure you wash your hands well, with particular focus on your fingers, using a non-perfumey soap. Perfume soaps have extra alcohols in them which can cause your blood sugars to falsely show as being high. Ivory soap or plain Dial soap and products like that are best, in my opinion.
Another common reason for such swings is that not all glucose meters are extremely accurate.