What happens if someone got pricked by a used needle with traces of Insulin ?

My sister got pricked with my grandmother's used diabetes needle. It contained traces of the diabetes medicine called "Mixtard". She is currently feeling feverish and the skin where she was pricked is a bit swollen and bluish in color. She is also feeling really sleepy but i dont know if that is an effect of the medicine. My sister is not diabetic and none of the above symptoms were present before this incident. What could be going wrong ? Thnx in advance.