I too was diagnosed with gestational diabetes. My daughter is now 7 months and I just did the OGTT last week as a follow up. My fasting was 81 and 2 hours after the glucola it was 79. The nurse I spoke with said 79 was on the low end of normal and asked if I ever felt shaky like my blood sugar was low. Every once in awhile I do get shaky and sweaty like you're describing. She said what can happen is when your body gets a lot of carbs at once the cf pancreas can give off insulin in surges resulting in a low blood sugar, perhaps this happens to you if you've eaten a lot of carbs at once? I am going to follow up with my Dr., but probably would be a good idea to check your blood sugars when that happens and keep a little snack with you at all times so it doesn't dip too low!