I would not say the only people are type 1, it can happen in type 2, but it is rarer. Anytime your insulin runs very low, which in some can be caused simply by biology. They do not produce a lot of natural insulin.
As in everything, there are studies and who knows if they will be proved cause and effect, I mean eggs, good, bad, good, bad, good, maybe. as one example, but it does not take more than 3 minutes to find credible articles. https://www.acc.org/about-acc/press-releases/2019/03/06/10/29/low-carb-diet-tied-to-common-heart-rhythm-disorder that is a study by the America College of Cardiology. I am not saying "Omg no, bad" just for anyone who is desperate, like some of us are, to look not only at benefit but risk, I weigh every single treatment I do in terms of "If it works, great, is it sustainable? Will it fit my life? Do I have a family history of something that this could make worse?" etc etc.
I suppose, I am cautious by nature and while I would love to see this as an effective long term answer for all, also feel people should know to look at the other side of the coin.
Even Batch strongly suggests/cautions to go over all of the Vitamin D regimen with a doctor.