Can trained dogs detect a hypoglycemic scent in patients with type 1 diabetes?

In persons with type 1 diabetes (T1D), hypoglycemia is common and sometimes serious. Anecdotal reports suggest that dogs can detect hypoglycemia in their human companions. The current study was undertaken to assess whether dogs can detect hypoglycemia by scent alone.

RESEARCH DESIGN AND METHODS

The study was approved by the Human Institutional Review Board and the Animal Care and Use Committee at Legacy Research Institute (Portland, OR). Three patients with T1D were enrolled (age 25–57 years; duration of diabetes 2–21 years; none were hypoglycemic unaware). These people were unfamiliar to the dogs that were studied. For each of two hypoglycemic periods (capillary blood specimens ≤60 mg/dL), each subject collected two sterile cotton swab samples by rubbing them on the skin of both arms. Additional samples were collected during two normoglycemic episodes (capillary glucose 100–150 mg/dL). This procedure was chosen because the dog-training organization affiliated with one of the authors used this method to train dogs to respond to hypoglycemia in their human companions. The three adult dogs used in this study had been trained to respond to hypoglycemia by pressing a bell after sniffing the open-capped container with the hypoglycemic swab. Each of these dogs had been placed in the home of a person with T1D. The owners and trainer believed that the dogs chosen for this study were consistently able to detect hypoglycemia in the home.

Investigators were blinded to sample identity. Each dog was tested with each of the 24 samples by presenting the sample to the animal for 30–45 s. An alert was recorded by a blinded investigator if the dog activated the bell.

RESULTS

Results are presented in Table 1. The values for sensitivity, specificity, and percent of samples that were correctly identified were each ∼50%. We considered the possibility that volatile compounds may have already evaporated during later tests. However, the first test was not more accurate than later tests.

Table 1

Human data and canine results

CONCLUSIONS

Trained dogs were largely unable to identify skin swabs obtained from hypoglycemic T1D subjects. We chose to test with skin swabs because 1) dogs are well known to respond to scents carried on human skin (1) and 2) the trainers had reported success with this method in training the animals to respond to hypoglycemia. To our knowledge, this is the first controlled study to address whether dogs can detect a hypoglycemic scent, though there are anecdotal and case reports suggesting that dogs can respond to hypoglycemia (2–4). Our results addressed only whether there is a detectable hypoglycemia scent on the skin. In future studies, it may be helpful to include behavioral elements, such as studies in the presence of human companions. It might also be helpful to obtain swabs from the usual human companions of the dogs. We found that trained dogs were unable to correctly identify skin swabs obtained during hypoglycemia in subjects with T1D. Further studies are needed to address the role of other factors that the animals might use, such as behavioral cues.