Over the past decade, as studies shed new light on blood glucose testing in human and veterinary medicine, veterinarians have responded with varying degrees of enthusiasm and caution.
Greet Van den Berghe, M.D., Ph.D., and her team at the Catholic University of Leuven in Belgium, have been studying the topic for the better part of 10 years. Dr. Van den Berghe’s original study, published in the New England Journal of Medicine in 2001, showed that intensive insulin therapy to maintain blood glucose at or below 110 milligrams per deciliter reduced morbidity and mortality among critically ill patients in the surgical intensive care unit.
This therapy was compared to the previously standard therapy, which involved responding only when insulin levels exceeded 215 milligrams per decileter and a maintenance of glucose levels between 180 and 200. This new therapy was called intensive insulin therapy.
Reid Nakamura, DVM, Dipl. ACVECC, of Red Bank Veterinary Hospital in Red Bank, N.J., says further veterinary research increased the excitement among veterinarians when it showed that patients with higher blood sugar levels had worse outcomes and longer hospitalizations.
“In 2008, though, the same Belgian group basically ran the study again on a larger population and found that patients who were going to be hospitalized for three to five days had a better outcome with intensive insulin therapy,” Dr. Nakamura says.
“Those who were going to be hospitalized for fewer than three to five days did worse. That kind of put the brakes on. Obviously you can’t tell who is going to be in the hospital for three to five days and who will be in for less time.”
The remaining question is what veterinarians can do with the information gleaned from research.
“We know that patients definitely tend to have a worse outcome when they have low blood sugar levels, but we don’t know if it’s a marker of a problem or if it’s the problem itself,” Nakamura says.
Despite these remaining questions, veterinarians are finding expanded uses for blood glucose testing outside of the treatment of diabetic patients.
“Especially in the emergency and critical care setting, we monitor glucose sometimes even hourly,” says James Barr, DVM, Dipl. ACVECC, who is about to join the faculty of Texas A&M University’s veterinary school.
“High glucose has all kinds of effects that we’re just starting to discover,” Dr. Barr says. “For instance, patients that have high glucose levels and have head trauma tend to do worse.”
Monitoring the fluctuation of glucose levels in non-diabetic trauma patients can be a useful way to track the seriousness of the trauma, Barr says.
Rita Hanel, DVM, Dipl. ACVIM, Dipl. ACVECC, agrees.
“Severe trauma patients often experience a massive sympathoadrenal surge,” Dr. Hanel says. “This will cause their blood glucose levels to markedly rise. If your therapeutic or resuscitative measures are successful, the glucose level should drop back down to normal.”
“The high blood glucose levels, we don’t necessarily treat unless it’s a prolonged high blood sugar,” Barr says. “Sometimes a patient who is in shock will have high blood glucose, but when you correct the shock, it will go down. If it doesn’t go down, then we need to take steps to lower it.”
Says Nakamura: “It’s interesting to monitor, but to be honest, we’re not really sure what we’re supposed to be doing with the information.”
Caution is important, he notes, because in human studies some individuals receiving intensive insulin therapy developed seizures.
While glucose levels are useful to the veterinarian in indicating the seriousness of the trauma, Nakamura believes decisions should not be made solely on the results of a blood glucose test.
“Pretty much everybody checks blood sugars, but I wouldn’t say anyone should be euthanizing on the basis of a blood sugar level,” Nakamura says. “We typically say, ‘Just give your pet 24 hours.’ In a patient that’s hospitalized and they might not be eating, they might have low blood sugar from that. More severely affected critical care patients might have higher blood sugar because of the severe stress response.
“It’s so controversial even in human medicine that it’s at the point where it’s a gray zone. As far as I am aware, no one does intensive insulin therapy in veterinary practice.”
“As we learn more about the prognostic utility of glucose monitoring, it will become more routinely measured and followed,” Hanel says.
“With the introduction of interstitial glucose monitoring, serial monitoring of glucose levels in the critically ill will become more practical and routine in the ICU setting. This is beneficial from both a prognostic and therapeutic standpoint and will require minimal blood sampling from the patient.”
Nakamura looks forward to more research: “At this point in time, we extrapolate a lot of the information from human studies, so in five or 10 years, when other studies come out and basically say yes or no, then there will be more veterinary studies. There has to be some other human-based research for us to explore the possibility of this.”
Barr says the research done has been groundbreaking, and he is certain that further studies will yield incredible results.
“I’m sure the person who found this (link between blood glucose levels and the probable course for the patient) is going to win a Nobel prize,” he says. “We knew that blood glucose being really high or really low were bad things, but it’s becoming even more evident now that small fluctuations can change the course for the patient.”
This article first appeared in the September 2009 issue of Veterinary Practice News