i obviously havent had GD, lol but i know that because insulin is a growth hormone it causes the placenta to have a shorter lifecycle, hence the early inducement. i know that most hospitals give u the option of very regular monitoring (ie every second day) if u decline the early induction so they can keep an eye on how the placenta is functioning and move quickly should they need to.
im not sure if its the same if u dnt end up on insulin though, wish i could be more of a help