You should definitely pose this question on the High-Risk pregnancy board...there are lots of us GD Moms on there and you can get all kinds of advice. Until you meet your dr and find out what your carb limits for each meal are, it's hard to give you specifics but know that protein will be your new best friend and you will need to watch the carbs you're having each meal...I can give you an example of what I ate today if that helps:
Breakfast (30 carbs or less) a whole grain bagel thin with laughing cow veggie cream cheese
Lunch (45-60 carbs) A McDonald's quarter pounder (no bun) med fries, and diet coke
Dinner (45 carbs or less) Shake and Bake buffalo chicken, broccoli, and potatoes o'brien (from a freezer bag)
You will also need to incorporate snacks between meals..at least one between each meal, but they told me I could eat every 2-3 hrs as needed. I get 15 carbs for a snack, so I can have 6 saltines with cheese, a nature valley protein bar, or a cup of milk
Finally, you will need a snack right before bed. My go-to snack is a tall glass of 1% milk with a tbsp of no sugar added Nestle chocolate drink mix. Make sure your nighttime snack has carbs AND protein, as it will be what controls your fasting sugar the next morning. Hope this helps, and like I said, check out the high-risk board