NEW ORLEANS — Specially trained service dogs are often able to detect hypoglycemia in people with type 1 diabetes, but in terms of accuracy, a continuous glucose monitor (CGM) is a patient's better friend.
So-called "diabetes alert dogs" are becoming increasingly popular, and patients often ask their physicians about them, but "limited studies of the ability of diabetes alert dogs to correctly differentiate between low and normal blood sugar have yielded conflicting results, although dog trainers and dog users are generally enthusiastic," Evan Los, MD, a pediatric endocrinology fellow at Oregon Health & Science University, Portland, said June 11, 2016 here at the American Diabetes Association (ADA) 2016 Scientific Sessions.
In his study of eight patients with type 1 diabetes comparing their own trained dog's alerts with both self-blood glucose monitoring and continuous glucose monitoring, the dogs did alert the owner 3.2 times more often during hypoglycemia (defined as a blood glucose level below 70 mg/dL) than euglycemia, suggesting that "these dogs really are detecting something."
However, just 12% of the 16 to 20 average weekly alerts occurred when the patient actually had hypoglycemia. "This has the potential to lead to overreliance on a suboptimally performing diagnostic tool that has significant financial cost and time investment," Dr Los noted.
And in events where both the dog and the CGM alerted, the CGM alerted first in 73% of events, on average 22 minutes before the dog.
In all, when hypoglycemia occurred, the first event was patient symptoms 12% of the time, dog alert in 19% of cases, but the CGM was far superior, detecting it 70% of the time.
Nonetheless, Dr Los pointed out that for people who don't have CGMs, a dog is better than nothing: "I don't think we would ever tell a patient to ignore hypo symptoms, so for a person who has a dog and finds it beneficial, I would never tell them to get rid of it, because it's alerting them to more hypoglycemia symptoms than they would otherwise know about."
What Are the Dogs Responding to?
Asked to comment, session moderator Lawrence S Phillips, MD, professor of medicine at Emory University School of Medicine, Atlanta, Georgia, said: "I think it's fascinating. But the question is, exactly what are the dogs responding to? To what extent is it behavior, or smell, or the threshold of the individual for changing behavior, autonomic responsiveness, or cognitive function as glucose levels fall?"
For example, Dr Phillips said, if an individual begins to feel symptoms and sweat or shake at a blood glucose of 100 mg/dL and that triggered a dog alert, that would have been counted as a false positive in the study.
"One would think there needs to be further investigation to try to tease out what the dogs are really responding to and if the comparison of the dog's response to an arbitrary CGM value of 70 is the fairest test."
Indeed, Dr Los said, "Perhaps understanding what factors impact dog reliability could help optimize dog performance."
Wide Variation in Training
Dr Los also noted that there is a great deal of variation in how these dogs are trained, although a typical method is to have them sniff cotton swabs of sweat from a person with hypoglycemia and then undergo focused training with the person they're assigned to. The process takes anywhere from 6 to 24 months and costs between $2500 and $25,000 for a fully trained dog. Trainers certify the dogs, but there is no universal test of competence.
The dogs also vary widely in age and breed, and it appears that more recently trained dogs are more reliable.
Dr Los commented, "This may not be the last word on whether diabetes alert dogs may be helpful. Perhaps having a neutral diabetes partner in the management of a chronic disease in which the daily tasks are not very rewarding provides a benefit not measured in this study."
Dr Phillips said that a patient who had both a CGM and a dog could analyze what the dog was responding to.
"That patient can then decide how it would be most appropriate to respond to the dog's signal. I think [dogs and CGMs] may potentially be complementary.…The other thing is, CGMs aren't warm and fuzzy or lick our faces."
Dr Los has no relevant financial relationships. Disclosures for the coauthors are listed in the abstract. Dr Phillips has served on scientific advisory boards for Boehringer Ingelheim and Janssen and has or had research support from Merck, Amylin, Eli Lilly, Novo Nordisk, Sanofi, PhaseBio, Roche, Abbvie, Vascular Pharmaceuticals, and the Cystic Fibrosis Foundation.
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American Diabetes Association 2016 Scientific Sessions; June 11, 2016; New Orleans, Louisiana. Abstract 76-OR/76
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Cite this: Aiming to Detect Hypoglycemia, Diabetes Dogs May Bark Too Often - Medscape - Jun 13, 2016.