What are the chances of getting hiv positive if you mistakenly pricked your self with an insulin injection of an hiv positive person?

This could be very high risk, depending in part on the infected person's viral load (i.e. how high the HIV RNA levels are in his or her blood). The pricked person probably should take post exposure prophylaxis (PEP) with anti-HIV drugs, ideally within 24 hours and for sure within 72 hr. See an experienced HIV provider immediately, perhaps the infected person's HIV doctor or clinic. Good luck.