Gestational Diabeties reading

I have Gestational Diabeties. My fasting glucose level was 86 and at breakfast i ate 1/2 cup boil oats and 12 pieces almond. After an hour my glucose level was 163. And then i go for walk for 20 min and i measure again 2 hr my breakfast and it was 96. Is this make that much difference after walk? Or May i got my result inaccurate? My glucose level is always below 130 after an after I finished my breakfast. Is this possible that glucose level suddenly drop from 163 to 96 in an hour?