Meaning, not how long until you run out, but how long until it degrades and you start seeing a difference in numbers and have to swap to a new one? My vet had mentioned 1 month. I've perused the threads here and see folks referring to 2 and 3 months. To me the true measure of it is actual data showing that its effectiveness has changed, which home testing nicely informs. So, just curious what folks have experienced with Vetsulin?