I'm also pleased to report that, for the second pen in a row, I've been able to get 60+ days out of our pen (antijinx is in order as I really would like to wait until Saturday to purchase a new pen!!).
I think two things have gotten me here... first, is pen care. at EVERY shot time, my goal is to have the pen out of the fridge no longer than 2 minutes, and the insulin exposed to light for no more than 30 seconds or so, never holding the pen around the part at which the insulin is contained (so as to not warm it with body heat from my hand). Also, I keep it in the very back of the fridge upright in a coffee cup that is elevated on another jar so I can easily reach it.
Second, in the past, once the pen is approaching/beyond 30 days, whenever Willie's numbers would start to creep upward, I think my natural inclination was to assume it was the insulin going bad, and I've simply suppressed that inclination and have made myself assume that it is the FD and not the pen and have adjusted the dose accordingly. A good example of this can be seen earlier this month. After a skipped shot on 2/24, Willie did see greens shortly thereafter, but his curve did widen so we were seeing preshot in the 140s to 150s. With the pen right around the 1 month mark, in the past, I'd have immediately assumed that the problem was failing insulin and would have tossed the pen. Instead, I upped the dose and found that his numbers came down. We hung out at that dose for over 30 cycles (mainly due to my not being around to test as much) and started seeing lower pre-shots, even earning a decrease just last week. And that's even with my habit of regularly shooting insulin back into the pen.
I share this because I know many here are on tight budgets, and while the method of FD management we practice here is very effective and I think contributes greatly to the health of our cats regardless of whether we ever see remission, it isn't cheap, and insulin can be the biggest cost. I think that with consistently meticulous handling of lantus, focusing on really minimizing time spent out of the fridge, exposure to light, and not wasting insulin (I used to draw 4-5 units each time and then get to the right dose, now I draw maybe a unit), you can easily extend the life of a pen if you're shooting at lower doses.
