Yes, Charlotte, you are 100% right.
At our birth center we have a 50 gram carb menu, and we have moms fast from midnight until the next morning. They are to finish consuming their breakfast one hour before their appointment (it is called a one hour post prandial test) I dont' know the menu exactly--there are two to choose from, but they include sugar in the form of a juice or jelly, protein in the form of milk or eggs, and carbs in the form of toast or breakfast cereal.
We are interested in how your body reacts to FOOD, not to a sugar binge. We certainly hope you aren't fasting for 12 hours, then drinking a coke and eating ho hos and ding dongs for breakfast!
As far as I know, we have had 3 women in 2 1/2 years fail the 1 hour post prandial. One had to monitor her diet and do regular finger sticks...the other did some dietary changes (though her diet was very good to begin with) and then she did fine. The other refused to retest, and we kept her in our practice (though she had a huge baby, with shoulder dystocia....). I think all or at least most of these women will end up with adult onset diabetes later on. I think that when we catch someone with "gestational diabetes" what we really are finding are women who all ready have some insulin resistance, but with the stress of pregnancy and the frequency of monitoring (I mean, how often is your blood sugar otherwise checked?) we discover them earlier in the disease process. Not saying that everyone who fails the sugar overload will develop diabetes later in life....I'm talking about a post prandial test. And it is just my opinion, but of course I like to share my opinion...