Hi there, if you're in the UK then yes, it would lead to an automatic 'restricted' licence but that basically means it's restricted to 3 years, ie, every 3 years you have to apply for a new one. Added to that is the proviso that there are certain questions you have to answer but these are in relation to the diabetes and are designed to make sure you have hypo awareness etc. What sort of job are you on about and what do you mean by unrestricted?, obviously if you are talking HGVs etc then it's different again.
Edited to add, ah, I see your title! What do the rules say for racing car Instructors? x