I had an amazing homebirth in October after a GD diagnosis, though it wasn't without a bit of drama at first.
My homebirth CNMs have to have OB backup. My original backup OB refused to be the backup after the diagnosis. We found another OB, but that would have meant birthing at the birth center rather than home. That OB also made the call right after the diagnosis (at 28 weeks) that I would need to be induced at 39 weeks in case of a large baby or other problems. After much research, I refused to consent to an automatic induction when there were NO indications of any actual problems. My midwives worked hard to find a third back-up OB - and the homebirth was back on with no pressure to induce as long as I took non-stress tests and everything looked good.
My blood sugars were really well controlled with diet, and I had NO PROBLEMS with the pregnancy. The non-stress tests showed everything was perfect. My blood pressure was great. Baby's heart rate was great. I measured right on target. There was NOTHING to indicate I needed to be induced. I ended up going into labor naturally at 40 weeks and my baby was only 6lbs 4 oz. I believe very strongly that an induction would have been an absolute disaster for me and the babe.
In my experience, controlled GD does not have to interfere with a homebirth. I would also hold strong against any blanket assumptions or calls for intervention made SOLELY because of the GD diagnois, in the absence of any actual problems.