Are you absolutely sure that your sausages were zero carb? Most sausages, unless very best, "home made" butchers ones, contain a lot of carb filler. Even one of our local butchers makes sausages which are full of honey. they are very popular, but for those of us not used to sugar any more, we immediately spot the (unpleasant) sweetness.
Sally
I am surprised that protein alone would cause such a spike at an hour. It is much slower release than carbs, and often doesn't take effect until several hours later.
It is easy to overlook carbs in sauces ect. Just when you think you have it figured out something else pops up for you to scratch your head over.