Nieko0423:Thanks! I'm trying not to, but DH has been super protective and watchful of how healthy I eat during my pregnancy and he's the one worried mostly. I have had my two best friends have very complicated pregnancy because of their health and diets and I have tried my best to stay as healthy as possible. I'm hoping everything turns out alright.

Gestational diabetes is caused by hormones the placenta makes. Some women can continue to produce enough insulin to counteract those hormones and others can't.
I had GD with my first pregnancy with no "triggers" - no family history of diabetes, within a normal BMI, healthy & active, non-smoker, was only 25, etc. So far my blood sugars have been on target this pregnancy without being diagnosed , so we'll see what my bloodwork says later this month.
Don't stress about it, there's nothing you could have done to prevent it if you do have it.