there is no where for blood to be trapped (airtight) on a lancet.
what is the difference between sharing "works" vs. a lancet?
Lancets don't inject. HIV is unable to reproduce outside its living host (unlike many bacteria or fungi, which may do so under suitable conditions), except under laboratory conditions; therefore, it does not spread or maintain infectiousness outside its host.
HIV is transmitted by;
Unprotected penetrative anal and/or vaginal sex
Sharing works with other IV drug abusers
Mother to child
HIV cannot be transmitted from a lancet. You have no worries. Your sister should be disposing of them properly, in a sharps' container, not in the trash. If her trash collection company sees that, she could be fined.
Tell her all she has to do is ask her doctor for sharps containers. When they're full...she can bring them back to her doctor's office...or any hospital.
Again....no worries at all.
she is also diabetic. that is what the lancet is from