Conference Coverage

VOC-sniffing necklace may support early detection of hypoglycemia



Patients with diabetes might soon be able to wear a necklace that warns of impending hypoglycemia 15 minutes or more before continuous glucose monitors notice a problem, according to investigators from Indiana University-Purdue University, Indianapolis.

M. Alexander Otto/MDedge News

Dr. Amanda Siegel

The device would detect changes in the volatile organic compounds (VOCs) that patients exhale as their plasma glucose level drops. In an insulin clamp study in 11 people with type 1 diabetes, the Indianapolis team found a marked shift in VOCs at a plasma glucose level of 90 mg/dL that persisted all the way down to a level of 50 mg/dL.

The team is now working on a sensor to detect that shift and alert patients. It’s the same trick that diabetes alert dogs do – minus the pup.

The device would be worn like a necklace, and “sense the air around your breath every 15 minutes or so,” said lead investigator Amanda P. Siegel, PhD, an analytical chemist and assistant research professor at the university.

Some continuous glucose monitors already warn of impending hypoglycemia, but the interstitial glucose levels on which they rely lag behind plasma glucose level by about 15 minutes or so. A VOC sniffer offers the hope of a real-time warning, Dr. Siegel said at the annual scientific sessions of the American Diabetes Association.

The team used gas chromatography–mass spectrometry to analyze 94 breath samples from the 11 participants, starting at a median fasting plasma glucose level of 150 mg/dL all the way down to 50 mg/dL, and back up to recovery. Samples collected at the 90-mg/dL and 80-mg/dL levels demonstrated VOC concentrations very similar to those at and below the hypoglycemia threshold of 70 mg/dL.

Even at 90 mg/dL, the VOC profile “looked like patients were already low. These volatile compounds change early” and stay on the breath as plasma glucose drops. “They are different from normal levels for the entire time, and separate out nicely,” Dr. Siegel said.

The team is not saying which volatile compounds are involved while the sensor is under development. They are looking for funding, and if all goes well, they hope to submit a device application to the Food and Drug Administration in 2020.

Other teams are also looking to VOCs to replace poor Fido, but he can alert to hyperglycemia and other problems as well, so his job is safe for now.

The work has been supported by the National Science Foundation. Dr. Siegel did not have any disclosures.

SOURCE: Siegel AP et al. ADA 2019, Abstract 968-P.

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