Like "Pens are pretty mucht he same as vials. I use vials and syringes. Damn, I wish my hospital offered the pens, but my plan states vials. Keep in fridge untill you start to use. when you start to use, take out, keep at room temp for 28 days. Here is a link to the American's Diabeteses association's take on this: http://www.diabetes.org/type-1-diabetes/safety.jsp Remember, pens and vials are interchangable in this article. "