That is because there is conflicting information. Some of the figures are based on in-house lab equipment. Some of the figures are based on outside testing lab results. Different labs have different reference ranges. Some of the figures are based on hand held glucometers. Some hand held glucometers are more accurate and reliable than others.
Some of the lab reference ranges have changed over time.
Normal feline BG can be from 74-143 on Idexx lab equipment. With the cats we have seen here over the decades, where most people use a human meter, a normal BG is <100 mg/dL, more often <80 mg/dL. My non-diabetic cat will test in the 40's to the 60's using a human meter. Human meters tend to read lower at lower numbers, numbers <100 mg/dL.
See how complicated it can be Perry?
My personal opinion, since there is not a body of evidence to support the range of normal BG levels on a pet specific meter, would be <120. But that should be without any insulin support.
My personal opinion is that even on the Alphatrak, 80-100 is a reasonable goal, if a cat is not getting any insulin, and is diet controlled.