absolutely not - we just had a cat, Mr Tinkles, following the Rand/Roomp protocol that is called Tight Regulation here, go off of insulin after 21 months. yes, it happens. i've seen it on more than one cat. at 3 months i think people are still mostly still figuring out how Lantus works - at least i was.
in fact, in the Rand/Roomp protocol the measurement wasn't at 3 months, the study was for 6 months.