I went into preterm labor and that is when I found out I had GD. I was in the hospital for 7 weeks and on a very strict diet. I took one shot of insulin in the morning and watched what I ate. I was allowed 15 grams of carbs for breakfast, 15 for a snack, 45 for lunch, 15 for snack, 45 for dinner and then 15 for a night time snack. I knew that if I ate to many carbs, it meant more insulin, and I did not want that. So if the cafeteria sent up something they weren't supposed to, I had a nurse on the phone right away. Juice is a big no no, it will shoot you sugar sky high. Bannanas aren't good either. Towards the end of my hospital stay, I could manipulate my menu so that all my food was carb free, and my 45 grams could be used for cheesecake. I impressed the dietician, I would even find errors in their menu, like if they listed the wrong carb count for things.
It is nothing that you are doing, it's just the way the body works. If you are able to exercise, I would suggest it. I was borderline with my first pregnancy and I think exercising was the only thing that kept me from insulin. As long as you do what the doctors tell you, everything will be alright. I know my dietician had said that they had women that were taking insulin and they wouldn't pay attention to the diet, they would eat more sugar. They figured they were already on insulin so eating sugar wouldn't hurt anything. They were very wrong. Just hang in there, you'll be fine. If you have to do insulin shots, they aren't that bad. And this is coming from a person so terrified of needles, that I went through 2 natural childbirths just so I didn't have to have an epidural.