Sniffing Out Hypoglycemia: How Dogs Can Detect Low Blood Glucose Levels

Exhaled Breath Isoprene Rises During Hypoglycemia in Type 1 Diabetes: S. Neupane, R. Peverall, G. Richmond, T.P.J. Blaikie, D. Taylor, G. Hancock, M.L. Evans. Diabetes Care Jul 2016, 39 (7) e97-e98; DOI: 10.2337/dc16-0461

What is the problem and what is known about it so far?

Hypoglycemia (low blood glucose levels) is an everyday concern for a person with diabetes and can be very dangerous. If a person experiencing hypoglycemia does not receive glucose, they can have seizures and become unconscious. In some people with type 1 diabetes these episodes can happen suddenly, with little warning. There have been reports of dogs alerting owners to changes in blood glucose levels.

Why did the researchers do this particular study?

Researchers suspected the dogs were detecting a particular chemical in exhaled breath, which might change when glucose levels were low. Researchers were interested in learning what, if any, chemical was responsible for the dogs’ reaction. If researchers know which chemical is raised during low blood glucose, they may be able to develop new detectors for hypoglycemia.

Who was studied?

Researchers studied eight women ages 41–51 years with type 1 diabetes.

How was the study done?

Participants' breath was collected in a bag while they had normal blood glucose levels and then again while they had high blood glucose levels. The breath samples were analyzed to determine which chemicals existed and how much of them were present. Researchers then compared the results.

What did the researchers find?

Researchers found that when blood glucose levels increased, a chemical called isoprene also had a major increase. No connection was found between isoprene and normal blood glucose levels. None of the other chemicals the researchers found showed any reaction to increases in blood glucose.

What were the limitations of the study?

Very few participants were included in the study, and all the participants were women. Also, the study was not able to clarify how hypoglycemia can increase isoprene levels.

What are the implications of the study?

These findings suggest that detection of a chemical in the breath called isoprene may offer an easy alternative to monitoring changes in blood glucose levels for people with diabetes. This also likely explains how dogs can detect (and can be trained to detect) low blood glucose levels in their owners.