I was told by the nurse at my PCP's office to keep my Lantus pens and Hummalog pens refrigerated at all times; however, the package inserts with both says to only refrigerate "unopened" pens and keep the pens in use at room temp or below 85degrees (F) and to also take new pens out of refrigeration a few hours before using. I do use an ice pack if I know I will be carrying my pens in temps above 75.
I have been following the package directions because the cold insulin often burned when I injected it. I haven't had any problems keeping my pens at room temp but I do sometimes worry that it might go bad. If you use pens, how do you store them?