Some doctors do just have to cover themselves.
However, if you are worried, and since you have had issues with gestational diabetes in the past (which might be contributing to the concern), simply be sure to pay attention to really good nutrition, getting enough protein, calories, and salt (to taste), and of course, staying well hydrated. While you are pregnant, that will keep your blood volume up and your baby well fed, and there won't be any issues with "sugar". Remember, your baby is fed from what is in your bloodstream, not your fat stores, so you naturally have more glucose in your blood stream during pregnancy - to feed the baby.
Your placenta causes a little "pool" between it and the uterine wall, where your arteries act like faucets and your veins act like drains, and your placenta has little "straws" called villa that suck up the nutrients from the pool, and release the waste from the baby to be processed by your body. As your baby grows, so does this pool, and your blood volume increases accordingly, to keep it fed. If your blood volume falls too low (decreasing the level of the pool), then your body starts increasing your blood pressure and holding water to try to keep that pool at the proper level. (The edges of the placenta act as a seal, so the pool stays where it is supposed to.) This edema and rising blood pressure (better to prevented) can sometimes be turned around by more protein, calories, salt to taste, and fluids.
Two really good sites with tons of information on gestational diabetes and preeclampsia, explaining what they are, what causes them, how to prevent them, and what to do if you get them, are www.blueribbonbaby.org and http://home.mindspring.com/~djsnjones/
It sounds like you and your baby are just fine, but knowledge is power. I hope this helps - good luck!
