There is no way to convert Relion numbers to AT2 numbers or vice versa. The pet meter will read higher than the human meter and the difference between the readings gets larger the higher the BG. And as mentioned, there is also meter variance which can make the numbers look quite different. What you need to know is that if the cat's BG is 68 or lower on the AT2 meter, that indicates BG is potentially dropping too low and action is needed immediately.
As Jayla indicated, Vetsulin is an in and out insulin and the drop starts earlier than Lantus and is often steeper and often the effect does not last a full 12 hours. Nadir can be anytime between 3 and 6 hours post shot in most cases. It's recommended that you do a pre-shot BG test, feed the cat, wait for 20 to 30 minutes and then give the insulin. You need to be sure kitty has eaten a good meal and that the food is staying down before giving the insulin.
If you will be visiting twice daily (as opposed to live in sitting) then you may want to discuss lowering the dose slightly for the time you are sitting the cat. Folks here often will reduce the dose slightly to ensure the cat, while unattended, will not drop too low. We also recommend not shooting at any reading under 200 on a human meter when there is little data or the cat will be unattended. On the pet meter, I would recommend a reading of 250 to 275 as the "no shoot" point but this is something you should discuss with the cat's caregiver. If the cat has been on Vetsulin for awhile and the cat is fairly well regulated, they likely have determined their own "no shoot" number based on their cat's reaction to the insulin and advice from the vet.
Every cat is different and with the caregivers home testing, I would hope they have historical data on which to reach decisions to keep the cat safe.
If you have any other questions, please let us know.
