I had gestational diabetes twice. The first time they gave my daughter formula but she was in an incubator so that was different I guess. The second time with my son (no insulin needed for me, just diet changes). They did not. He lost a little over 10% so they tried to convince me, but no he didn't really need it and they did not give it automatically. What might happen is that the blood sugar level of a newborn goes to far down if mom had gest. diabetes. In case of such an hypoclycemia they may have to give your baby some glucose solution (out of a bottle???), but this is just once to normalize blood sugar and it is done after testing and has nothing to do with formula. But hey, I heard when my son was born, that they don't want to do this anymore (I don't remember why) so maybe they switched to formula instead??.