Per Novo Nordisk, the manufacturer of Levermir insulin, unrefrigerated pens are to be discarded 42 days after it is first left out of the refrigerator. Unfortunately, once they are left out at room temperature, they cannot be returned to the fridge to prolong the expiration date.
Although such a short time out of the fridge is unlikely to dramatically lower the overall effectiveness of the Levemir, studies have shown that there is in fact a small drop in potency if left unrefrigerated. It is very important to be confident in the stability and potency of your insulin product. Small changes in dose can have a large impact on your blood sugar levels.
Insulin pens such as Levemir can be very expensive to replace, especially if you need to pay out of pocket. We recommend contacting your pharmacy and have them reach out to your insurance company to see if they will cover a replacement pen. If that route doesn't work, your doctor may have samples they could give you to hold you over until your next fill. In neither option works, you may be able to buy a single pen at your pharmacy. We also recommend that you discuss with your doctor other options that they may be aware of to help you get a replacement pen.