Baby number one was born at 34w 5d due to severe pre eclampsia, weighing 5lb 12oz which happened to be exactly on the 50% line for the weeks gestation, but because it was before the fattening weeks in the womb (as it were!) he looked a right skinny little thing! He had to go into an incubator under lamps for jaundice & be fed via nose tube for a day or two. HbA1c was typically around 6 during this pregnancy.
Baby number two was born at 35w 6d, macrosomic, weighing 7lb 13oz. She had to go to the SCBU for a few hours' obs & extra feeding due to a bit of 'grunting' when breathing & a slightly low sugar level of 2.3, despite their telling me that anything above 2 is normal for a newborn. She had jaundice but didn't need phototherapy. The HbA1c during this pregnancy was even better, at best being 5.7. When I spoke to the consultant about this, he said that my control had been oustanding & the macrosomia was just a factor of how long I'd had diabetes (31 yrs) so not to feel bad...
Unfortunately it seems the docs just tend to apply broad brush strokes to their opinions of things, ie diabetic = fat baby because of poor control. Not true, and not fair. Another one that gets my goat is the assumption by medical professionals that I have proliferative diabetic retinopathy because "obviously" i don't care about my diabetes & have poor control!!! Nothing to do with 31 yrs diabetes with old (inadequate) control methods during the challenging periods of infancy, childhood, adolescence, uni & 2 pregnancies then?! Sorry, ranting off the subject.
Anyway, my experience is that T1 diabetic does not necessarily mean a fat baby, and a fat baby does not necessarily mean you have had poor control!
Hope that helps! 🙂