Hi Dara,
I used the Alphatrak 2 and a Relion Confirm for a short period of time in parallel testing. Yes, there are number differences. The differences are about 30 points at the low end. A bit more at higher numbers.
You do not ever need to add points to any reading you get with any meter you use, be it a human glucometer or a pet glucometer. As long as we know which type of meter you are using, we can interpret the numbers you are getting.
I finally talked the cat shelter into paying for the lower cost Relion Confirm test strips to save a lot of money. It took me more than a month to convince them but when I did, and they saw how much less the Confirm test strips were, they were very pleased.
Price is a big factor in people switching from the Alphatrak to a human glucometer. Many of us do that to save money. In fact, a lot of our members in Canada wish the Relion line of meters were available there. A few even drive across the border periodically to buy test strips, if they live close enough.
The 100 point difference you got could be from many factors. Even using the same glucometer to test the exact same blood drop can give you different readings. All meters are allowed to vary from reading to reading, by +/- 20%.
I would estimate that 90-95% of people here use the less expensive human glucometers for testing their cats.
Vets may disagree, but the numbers we get are close enough to be able to see what is going on with the blood glucose levels and make adjustments in the dose. I have heard from some people here, that their vets use human glucometers.
I would recommend the Relion Confirm for the low cost of the test strips, $0.36 each and small blood drop size, 0.3 microliters. The Relion Prime requires a slightly bigger blood drop, 0.5 microliters and seems to get more errors because of this than the Confirm. Selling point for the Relion Prime is $0.18 each for test strips, half the price of the Confirm test strips. If you are not so good at home testing, the Prime and the larger blood drop can present some challenges.
Think about the pros and cons of the Confirm and Prime and decide which one you want. I would feel confident in recommending either one to you.