I used to read about insulin expiring and think that that had never happened with me. Then I decided to do an expiriment; use a Lantus vial until something wacky happened.
I had used the same, outside the fridge vial for 56 days when I woke up one morning with a 357. I had woken up high the previous three days, while going crazy low during the day, so at that point I decided to open a new Lantus. My morning numbers became much better.
With the new knowledge that Lantus acts quicker the longer it's left out of the fridge, I looked back and noticed that even before the month expiration, my overnight numbers get worse; the week after I open a vial, my numbers are mysteriously beautiful.
Right now I'm on a road trip, and I packed insulin. I decided to take only one vial of Lantus, and at the first sign of expiration, to begin splitting the dose. So this morning, I was up at 4 AM and my bg was 89. At 9 AM when I got up, it was 159. So I decided to take 12 units of Lantus at that time, an extra breakfast Novolog unit, and at 9 PM I took 6 units of Lantus. Tommorow morning, I will take 8 units, and twelve hours later the same, splitting my dose for the rest of my roadtrip.
I left on Sunday, June 24 and had euglycemia (sort of- between 60 and 180) until Saturday, with one exception of hypoglycemia when I forgot to eat my supper after I injected for it. I will be back home on Friday.