Diabetes Sniffer Dogs? Chemical in Human Breath Signals Low Blood Glucose Levels

Isoprene breath test may replace finger pricks for diabetes patients

A chemical found in human breath could provide a red flag for dangerously low blood sugar levels in patients with type-1 diabetes (T1D), according researchers at the University of Cambridge in the United Kingdom. The finding, published in Diabetes Care, could explain why some dogs can be trained to spot the warning signs of hypoglycemia.

Claire Pesterfield, a pediatric diabetes specialist nurse, has T1D. She also has a golden Labrador dog, “Magic,” that has been trained by the charity Medical Detection Dogs to detect when her blood sugar levels are falling to potentially dangerous levels.

“Low blood sugar is an everyday threat to me, and if it falls too low––which it can do quickly––it can be very dangerous,” Pesterfield said. “‘Magic’ is incredible––he’s not just a wonderful companion, but he’s my ‘nose’ to warn me if I’m at risk of a hypo [a hypoglycemic attack]. If he smells a hypo coming, he’ll jump up and put his paws on my shoulders to let me know.”

Given the numerous reports of dogs alerting owners to blood-glucose changes, researchers at the University of Cambridge believed that certain naturally occurring chemicals in exhaled breath might change when glucose levels are low. In a preliminary study to test this hypothesis, the scientists gradually lowered blood sugar levels under controlled conditions in eight women with T1D. The investigators then used mass spectrometry to detect the presence of these chemicals.

The researchers found that levels of the chemical isoprene increased significantly in hypoglycemia. They believe that dogs may be sensitive to the presence of isoprene and suggest that it may be possible to develop detectors that can identify elevated levels of isoprene in the breath of patients at risk of hypoglycemia.

“Isoprene is one of the commonest natural chemicals that we find in human breath, but we know surprisingly little about where it comes from,” said investigator Dr. Mark Evans. “We suspect it’s a by-product of the production of cholesterol, but it isn’t clear why levels of the chemical rise when patients get very low blood sugar.

“Humans aren’t sensitive to the presence of isoprene, but dogs, with their incredible sense of smell, find it easy to identify and can be trained to alert their owners about dangerously low blood sugar levels. It provides a ‘scent’ that could help us develop new tests for detecting hypoglycemia and for reducing the risk of potentially life-threatening complications for patients living with diabetes. It’s our vision that a new breath test could at least partly––but ideally completely––replace the current finger-prick test, which is inconvenient and painful for patients, and relatively expensive to administer.”

Source: University of Cambridge; June 27, 2016.