Point-of-care glucose meters, or glucometers, have revolutionized the landscape for diabetics and practitioners. Using only a small drop of blood to measure blood glucose in an instant, they make it easier for people with diabetes to maintain their levels in a healthy range. Pet owners, too, sometimes rely on glucometers to monitor their diabetic animals.

Glucometers are also used in human and veterinary hospitals to monitor emergency and critical care patients.

The only problem? 

“They can be a little inaccurate,” says Rebecka Hess, a professor of internal medicine at the School of Veterinary Medicine. “Up until now we’ve just lived with it.”

To find a way to improve the accuracy of glucometer readings, Hess and colleagues at Penn Vet tried something new. With the permission of pet owners, they obtained blood samples from cats and dogs that were being treated at Ryan Hospital and were having blood drawn for another purpose. Instead of just using whole blood in the glucometer, they also tried measuring blood glucose using blood plasma, which is what remains of whole blood after removing red and white blood cells, and blood serum, which is what is left of blood plasma after also removing clotting factors. Plasma and serum can be obtained from whole blood by spinning a sample for a few minutes in a centrifuge.

The scientists compared the glucometer readouts against the “gold standard” method of measuring blood glucose, using a biochemical analyzer. Reporting their results in the Journal of the American Veterinary Medical Association, they found that both plasma and serum resulted in more accurate measurements of blood glucose compared to whole blood.

Both gave readings that correlated closely with those of the biochemical analyzer.

The findings suggest that the speed and convenience of a glucometer doesn’t have to come with the tradeoff of less accurate blood glucose readings. Already, Ryan Hospital has changed their practices to use plasma or sera instead of whole blood when measuring blood glucose with a glucometer.

“It’s a simple study but it has changed the way we do things,” Hess says.

The team says that if the findings are replicated in humans, it could change the way diabetics monitor their own blood glucose levels at home.

“I can easily envision people purchasing centrifuges at home for this purpose,” Hess says.