It's crazy isn't it! The main risk for the babies for GD is getting stuck during delivery and the normal risks associated with c-section. Well, early on (1st tri) it can cause miscarriage I think but not really sure how. The other concern is that the baby's blood sugar is high if the mom's is, so when the baby is born it's blood sugar can drop as it's not getting it from the mom. But usually it's fine if the doctors are aware of it.
I can't imagine having a newborn that big, I agree about feeling cheated out of the wee baby stage. Also, I would always be concerned about their weight compared to that of their peers.