Welcome back, Heatherok. Good luck on your goal of reversing your diabetes.
To me, the most obvious reason for choosing a primal diet over a juice fast is that you will be able to continue with it for the rest of your life of continually improving health while a juice fast is obviously a temporary measure.
I don't know very much about diabetes but it seems to me that it would be a good idea to limit fruit at first as they are very high in sugars, and concentrate more on veges which are a very important source of nutrients. I don't see why you shouldn't eat primal meats and eggs and juice your veges if that will help you eat more of them while you are starting out. But in the long run it would be desirable to learn lots of delicious ways to serve them. Good luck.