Opened vial of insulin can be stored for four weeks in warm temperatures, without loosing efficacy

Research found that the insulin preparations recorded a potency loss of no more than one percent — the same as in a control batch kept in cold storage.

from http://www.firstpost.com/health/opened-vial-of-insulin-can-be-stored-for-four-weeks-in-warm-temperatures-without-loosing-efficacy-9270681.html