Truth Behind Diabetes Detection By Dogs Revealed


For years we’ve heard stories of dogs rushing to the aid of ill owners, sniffing out medical ailments before they’re diagnosed and trotting around with a general unexplainable awareness of our bodies. This mysterious ability to detect ailments sounds a bit far-fetched, but anecdotal evidence has again and again pointed to the fact that dogs know something more than we do. It turns out they do.

A study by researchers from the Wellcome Trust-MRC Institute of Metabolic Science at the University of Cambridge has discovered that the unknown smell dogs are most likely detecting is in fact isoprene, a common natural chemical in human breath that increases when blood sugar levels drop dangerously low. Our olfactory senses are far too dull to detect such a change, but any shift in isoprene is easy for a dog to detect.

So, if you have type 1 diabetes, it turns out a dog’s nose can indeed possibly save your life by detecting and pointing out an impeding hypoglycemic attack and allowing you to get a sugar boost before suffering a seizure or losing consciousness.

The study, which was published in this month’s issue of Diabetes Care, examined eight women between the ages of 41 and 51 with type 1 diabetes (T1D). Under controlled conditions, researchers lowered the women’s blood sugar levels and looked for changes in specific chemical signatures. They found that as blood sugar dropped, breath-exhaled isoprene rose, nearly doubling in some cases.

The study followed reporting from The Washington Post and National Geographic on the case of Jedi, a black Labrador retriever and trained diabetes alert dog (DAD) who alerted the mother of Luke Nutall, a 7-year-old with T1D, to her son’s dangerously low blood glucose levels one night while the boy slept. Luke’s nighttime continuous glucose monitor (CGM) was showing a healthy level, but after being awoken and repeatedly warned by Jedi, Luke’s mother, Dorrie, pricked her son’s finger and found his blood glucose levels were in fact half what the monitor was reporting.

Other stories of medical alert dogs intervening to aid T1D patients are common. The problem is that diabetes alert dogs are hard to train and often prohibitively expensive. Traditionally, trained DADs have required an initial adoption fee of as much as $20,000 (Heads Up Hounds). The nonprofit Dogs Assisting Diabetics estimates that in addition to an adoption fee, patients must pay an additional $1,000 a year for food, medical care and other expenses.

The fact that a diabetes dog can detect dropping blood glucose levels (BGLs) and alert an owner by performing a trained task—in the case of Jedi a repeated bowing motion was the trained tell—is an empowering tool for many. But what if dogs aren’t an option for you or simply aren’t your thing? The hope here is that in the near future a breath-based sensor that alerts elevated isoprene levels and warns of possible hypoglycemia can be developed. Research on that task is already underway. While a breath sensor is unlikely to completely supplant the current finger prick test that T1D patients use, it would be a valuable and non-invasive addition to one’s treatment toolkit.

Learn more about Diabetes Alert Dogs and read Maggie Jones’ advice: Consider This Before Getting a Diabetic Alert Dog.

WRITTEN BY Greg Brown, POSTED 07/27/16, UPDATED 08/24/23

Greg Brown is a freelance health, finance and environmental writer living in the mountains of western Maine. He has written for Consumer Reports Magazine, Consumer Reports Online, The New York Times and The Chicago Tribune, among other publications. He holds an MFA in Fiction Writing from the University of Iowa Writers' Workshop and an MS in Journalism from Columbia University. He can be reached at