Alphatrak vs human glucometer

I’m not sure if this is the correct place to post, so I apologize in advance if it is not.

My cat was diagnosed with diabetes about two months ago. This forum has been super helpful for me! After reading the boards regarding glucometers I decided to go with the Relion Confirm rather than the Alphatrax due to cost.

My vet was concerned about discrepancies in my meter vs the Alphatrax, so I went in with my cat to compare readings on the two. My human meter read 120 mg/dL lower than the Alphatrax. Needless to say, a difference that significant could impact the overall heath of my cat.

I wanted to share this in case anyone else has chosen to use a human glucometer, it may be a good idea to check it against one specifically made for animals.

 

Human meters read lower than pet meters because of the different distribution of of glucose in the blood constituents. The difference is proportional the the BG value. There is a larger difference with the BG is higher. There is not conversion fact to change a human meter value to a pet meter/vet machine value

Blood Glucose Meter for Cats
Facts:
Blood has two constituents, the red and white blood cells and the liquid (serum). Blood plasma is blood serum without the clotting factor
The blood glucose value obtained via laboratory analysis is the glucose level in the serum/plasma constituents of blood
The glucose is in both the serum and red-blood cells (RBC) themselves. However, the distribution of glucose is different between humans and cats (and dog too)1
In Humans 58% is in plasma/serum and 42% in RBCs
In cats 93% is in plasma/serum and 7% in RBCs
In dogs 87.5 % in plasma/serum and 12.5% in RBCs.
The point-of-use blood glucose meters (the ones we use at home) all use whole blood.2 However, what specific blood glucose they measure varies with the manufacturer. Some manufacturers only measure the glucose in the serum/plasma. Others lyse (disrupt the cell walls of the RBCs) and thus mix the glucose that was in the RBC into the liquid and thus measure total glucose. The meters then correct/adjust the reading to be equivalent to human blood plasma
Discussion:
Since the glucose distribution is different n humans and cats/dogs the resulting BG valve obtained from the human meters will be different that lab values and animal-calibrated meters. Also, some manufacturer's meters will be much different that lab values for animals depending upon which method (lyse cells or only use plasma/serum) they use to measure glucose.

Animal calibrated meters correct the value to be equivalent to lab values.

What clouds any BGs obtained from hand-held meter is that they are only accurate to +/- 20 %. That includes the animal-calibrated meter. Also, do not confuse accuracy with reproducibility. It is expected that one meter with one lot of tests strips to be relatively repeatable, that is if you use the same drop of blood, you BG value will be much close than +/- 20%

References:
1 Different Species, Different Blood
http://www.vet-advantage.com/dsr_library/get_file.php?file_id=161
2. Glucose Meters: A Review of Technical Challenges to Obtaining Accurate Results
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769957/

 

The difference is less at lower numbers... So a 50 on a human meter is about a 70 on an Alphatrak... But the difference is significant at higher numbers... So a 350 on a human meter might be a 450+ on a pet meter.

I like my numbers to match the vet so I opted for the Alphatrak.