diabetis while pregnant

i had my sugar test done and it was like really high so know they gave me a diet to follow most of the time i check my blood it is in the range they told me (less than 140 after meals ) but i have had it higher in certain occasions my qs is what should i do when this happenes my doctor said to call him if it got to 200 but what if its just a couple of # above 140 what do i do and is this harming my baby if it keeps happenming should i ask for medications just to be on the safe side whats better for the baby??????confused all this is so new to me help thanks in advance :)