Again, I don't have scientific data, only personal experience - I am a diabetic, and protein has had no impact on my blood sugar readings, unless I am still combining it with carb foods. I think the point is that you can't know how your body will adapt until you've tried it, and the perpetual fear keeps people from trying. My reading online indicates that once you stop overloading with carbs, in most cases diabetes is reversed or "cured". (I am a big fan of the writings of Dr. Jason Fung, but can't post a link with this phone. He is not a zero carb guy, he is an intermittent fasting and lchf guy, but the info is relevant.). I can't speak with authority on anything because my diet bounces with availability. I'll spend a few days zero carb, a couple weeks lchf, fast a couple days, and then get hungry enough that I go back to carbs from the garden.
A concern I have had is this: I have no gall bladder. Thus I question my body's ability to extract the nutrition it needs from a lchf or zero carb diet. But rather than say, I can't do it because I have no gall bladder, I'd rather do it and see for myself...and so far, I haven't keeled over from malnutrition, and I still feel my best when I eat the least carb.