With both of my boys I was gestational and on insulin. If you do fail the 3 hour test, you will meet with a nutritionist. She will help you based on your weight and past history with food design a plan for you to eat. Basically it is about balancing proteins with the carbs. Never eat just a carb. Always have a protein with every meal. Another important item is to eat every 2-3 hours. So for example my "sample" meal plan for the day was:
(1 protein=7 grams protein, 1 carb=15 grams carbs)
B- 2 proteins and 2 carbs
S- 1 protein & 1 carb
L- 2 proteins, 2 carbs, 1 fruit + veggies
s- 1 protein, 1 carb,
D- 2 protein, 2 carbs, 1 fruit + veggies
S- 1 protein, 1 carb, 1 fruit
I cannot have milk since I am lactose intolerant. That would have been figured into some of those carbs areas. Veggies were permitted at each meal. I was also allowed so many fats per day, but this should give you an idea as to a sample meal schedule. They met with me after one week to see how I was doing on the diet, if I felt like I was getting enough food... One thing that they did tell me was to not eat any fruit before lunch time. For some reason it really was not good for gestational diabetes.
Excercise is also really important. That really lowered my sugars and helped me lower my amount of insulin I needed to take in. My biggest problems were in the mornings.
I hope this helps. It is really good to eat this way during your pregnancy anyway. The healthier you eat before you deliver, the healthier your baby is after.
Good luck. The drink tasted like a sweet crush soda. They also asked me to eat three candy bars (one candy bar per day the three days before my test). Did not know what that was about, but ok...