Whether for humans or for pets, monitoring blood glucose is essential for those with diabetes. Regular monitoring can help you to keep blood glucose in range and to become aware of triggering factors responsible for blood sugar spike or fall. It can also help to detect potentially dangerous conditions, such as hypoglycemia or diabetic ketoacidosis. Nowadays, hand-held glucose meters (a.k.a. point-of-care glucometer or POCG) specific to dogs and cats are readily available to provide a convenient way to check their blood glucose levels at home.

You may ask, then, how does a pet-specific glucose meter differ from a glucose meter for humans? The main difference between the two comes from how they are calibrated.

What does a glucose meter measure?

Your whole blood is composed partly of liquid and partly of solid. The liquid portion of the blood is called the plasma, which is made up of water, salts, and proteins. The solid part of the blood comprises largely of red blood cells, along with white blood cells and platelets. Most home meters are designed to take your whole blood sample but to calibrate the reading to a “plasma-equivalent glucose concentration.”

This calibration method may be due to a variety of reasons, but one practical benefit is that lab biochemical analyzers also usually give a reading for plasma or serum glucose concentration. This makes it easier to compare the results at home to the ones taken at the vet. Some studies (Tauk, 2015; Gohlke, 2017) also reported that when measured by a POCG, glucose concentration in plasma is more accurate than a whole-blood glucose concentration when compared to results from biochemical analyzers in clinical diagnostic laboratories.

How is the calibration affected by plasma-equivalent glucose concentration?

Humans, dogs, and cats have unique distribution of glucose in their blood.

• In humans, the glucose concentration of plasma is roughly similar to the glucose concentration of red blood cells (ratio of approximately 1:1).
• In dogs and cats, on the other hand, the ratio of glucose distribution between plasma and red blood cells shows a large gap.
  • For cats, it is reported that 93% of glucose exists in plasma while 7% exists in red blood cells.
• For dogs, it is thought to be 87.5% of glucose in plasma and 12.5% in red blood cells.

Since a human glucometer will not take into account the difference in blood glucose distribution for different species, its calibration will likely underestimate the blood glucose value when used on cats or dogs.

Other benefits of using a pet-specific glucose meter:

• Less blood sample required for testing: The minimum blood sample required to process the reading may differ across different products/manufacturers. Still, in most cases, a minimum of 0.5 uL (microliter) of blood sample is necessary for human glucose meters. Pet-specific glucose meters, however, usually require less: a minimum of 0.3 to 0.4 uL.
• Pet-specific glucose meters are especially useful for cats, who often experience stress hyperglycemia. Settings unfamiliar to them, like going to the vet, may often produce an inaccurate representation and show a reading higher than their actual blood glucose level.

Whether it be to check the effectiveness of insulin or to prevent life-threatening situations, the reliability of glucometers is important in order for it to be a useful tool. Using a glucometer specifically calibrated for dogs and cats can be a good starting point in monitoring your pets with diabetes.