I believe the dry fasting is supposed to accelerate autophagy and/or possibly weight loss. Not necessarily part of diabetes management. I also think it is only done for short periods. I recall people talking about doing it for 12-18 hrs. Much like the religious fasting of Ramadan (? can’t spell, sorry).
As I said, I doubt it is something I would do. It is just interesting, especially since I seem to see more people recommending it and talking about it’s benefits vs those of water fasting.