Lab tests (blood and urine) are more conclusive than looking at bubbles in your pee & whether they pop or not and trying to determine if it is actually bubbles, foam or froth.
It is true that too much protein is hard on kidneys. I know this because I am also diabetic and was trying to limit carbohydrates. I was loading up on protein. But it is not just a generalized thing. Certain kinds of protein are worse than others (such as red meat). Besides you do need a healthy balance of all the food groups.
You mentioned that you were eating the protein bars for the fiber. Have you been told to increase your fiber? If you can see a dietician or nutritionist you can get lists of foods that have high fiber. You can also get advice on types and quantities of protein to suit your particular situation.