Feline Responses to Hypoglycemia in People with Type 1 Diabetes

Dear Editor:

Hypoglycemia is a common and potentially hazardous complication of diabetes, typically occurring in people being treated with insulin. Despite the potentially wide range of hypoglycemia-induced signals (e.g., tremors, tachycardia, sweating), people with diabetes often experience poor awareness of their own symptoms, with accuracy of detection generally waning over time due to the effects of advancing age or complications of the condition, such as autonomic neuropathy. ¹ Although numerous techniques (e.g., glucose sensors, skin conductors, heart-rate monitors) have been developed to facilitate early detection of hypoglycemia, ^2,3 none of these, as yet, are considered reliable, practical, or suitable for use outside clinical settings.

Evidence now suggests that some domestic dogs may be able to detect hypoglycemia in their human caregivers, and, as such, might have the capacity to serve as an early warning system for people with diabetes. Wells et al. recently reported a survey in which almost two thirds (65.1%) of respondents (n = 212) with insulin-treated type 1 diabetes believed that their pet dog had shown behavioral responses to their hypoglycemic episodes on at least one occasion. ⁴ Similar, more anecdotal, claims have been reported by others. ^{5 –9}

Although all of the published research in this area has focused on the ability of the domestic dog to detect hypoglycemia, it is plausible that other species might also be sensitive to changes in people's glucose levels, and may thus have a role to play in improving the welfare and quality of lives of individuals with diabetes. Here we report, for the first time, five cases of the domestic cat showing behavioral responses to their owners' episodes of hypoglycemia.

Five (5) cat owners spontaneously contacted the lead author by e-mail in response to a worldwide call requesting help with participation in a project aimed at exploring the ability of dogs to detect hypoglycemia. Quantitative data were not collected from these individuals (since the study was concerned with dogs' reactions to hypoglycemia); however, their detailed e-mails provided a wealthy source of information, relevant elements of which are presented hereafter.

The 5 individuals who contacted the author were adults with type 1 diabetes (3 women, 2 men). The cats (2 males, 3 females) represented by the patients were of mixed breed, and included a Persian, Burmese, and 2 crossbreeds; one of the cat's breeds was unspecified. Four (4) of the cats resided in a house with no other pets, while one animal shared its home with a dog.

All of the cats were reported to have shown behavioral responses to their owners' hypoglycemic episodes on at least 5 separate occasions (range = 5–12 times). Behavioral responses varied slightly between individual animals, but were largely consistent. All of the cats were reported to have “alerted” their owners at night-time. Three (3) of these animals slept in the same room as their owners, and typically awoke the caregivers by jumping on top of them, and nuzzling/pawing at their faces. Two (2) of the cats did not sleep in the same room as their owners and, in both cases, scratched at the closed bedroom door, causing the caregivers to awaken. One (1) of these animals reportedly had chronic arthritis in her paws, rendering this type of action difficult. Two (2) of the cats were also reported to display “alert” behavior during the daytime. In both cases, owners described a pattern of action in which the animals stared continuously at their faces, and, in the event of moving around the house, followed them from room to room. In all cases (whether at night-time or daytime), owners reported that it was their pets' rather unusual, out of context, behavior that triggered their suspicions that something was wrong, prompting them to check their glucose levels, which in all cases were found to be very low. Similar patterns of behavioral response to hypoglycemia have been reported by owners of domestic dogs, ⁴ leading us to hypothesize that similar mechanisms underlying detection might be at play in both species.

Dogs are now routinely trained by various organizations around the globe as a noninvasive alert tool for people with a wide variety of conditions (e.g., epilepsy, cancer), including hypoglycemia, e.g., Support Dogs, UK; Dogs4Diabetics, USA. ¹⁰ Although more empirical data need to be collected, we conclude that other species, such as the cat, may also have a role to play in the detection of certain underlying physical ailments. Whether this species offers the same ease of, or degree of flexibility in, training is still unknown, but certainly warrants future investigation.