As a gestational diabetic for the 2nd time now, I will tell you some "tricks" about eating that may help. I test my blood sugar 2 hours after eating. So, because you can't fast (which blood sugar is sometimes higher in the morning anyways) I would suggest making sure your lunch is at least 2 hours prior to your appointment. Also, eat a high protein lunch. Meats (if you are not vegetarian) and cheese do not elevate your blood sugar, but can stabilize it. Vegetables are also very low in carbs. I would also avoid fruits and especially fruit juices (even 100%) because they tend to spike your blood sugar levels quicker (even though they are natural sugars). Stick with water, coffee, or unsweetened tea (or if you are ok with artifical sweetners diet beverages) to drink.
Ultimately, if your body is insulin resistant, it just is. But I understand doing what you can to avoid it. I will say that if you are gestational diabetic, it is not that bad. During my first pregnancy, I was able to control my levels with food and a low-dose prescription (pill). But during this pregnancy (and we caught it much earlier this time), I am on 3 different types of insulin with 5 injections a day. As my doctor put it, when my body has a placenta in it, my insulin doesn't work on its own.
If you have any questions, please do not hesitate to contact me! Best of luck!