It is true that EXCESS protein will be converted to sugars. As long as you limit your protein intake it will be used exclusively for housekeeping. That's why keto diet is not only carb elimination, it is carb elimination WHILE restricting protein to about 30% of your calorie intake.
It is exactly this reason why keto diet is so hard to maintain -- because you have to fill the rest with fat and this is a hard thing to do.
> Please understand that diabetes is an old and very well researched condition.
It is funny that you mention it, because do you know what was the actual first treatment for diabetes? Before they were able to produce insulin?
It was actually eliminating carbs from the diet. Yes, in the past, keto diet was the main (and the only) way to treat diabetes.