regarding genetic disorders related to protein production
There are many protein deficiency issues caused by genetic mutation for eg: Protein C whose deficiency causes abnormal blood clots. This protein is controlled by the PROC gene whose mutation causes Type I Protein C deficiency (reference). 

There are treatments of replacing proteins like in the case of Protein C deficiency, protein C concentrates are used (reference). In the case of Alpha-1-antitrypsin (AAT) deficiency, augmentation is done with weekly intravenous infusion of the AAT protein (reference). 

So in many cases protein is actually supplied from outside the body and also many protein deficiency conditions can actually be controlled with balanced diets (reference) which unfortunately is not a solution for insulin deficiency.