Often Type 1 diabetes  patients have difficultly telling when they have low blood sugar levels, a problem called impaired awareness of hypoglycemia.

To offer a solution, researchers from the Radboud University Medical Center in Nijmegen, Netherlands have  developed a new wearable medical patch that measures variations in heart rate, which could be used for early detection of low blood sugar in patients with Type 1 diabetes.

Hypoglycemia is common in children and adults with Type 1 diabetes. Severe hypoglycemia, when untreated, can lead to seizures, loss of consciousness or possibly death.

Glucose meters inserted under the skin can help identify hypoglycemia, but they often come with a delay.

“This delay can compromise the accuracy of measuring low glucose values,” the study’s principal investigator, Dr. Marleen Olde Bekkink, PhD, an endocrinology fellow at Radboud University Medical Center, said in a statement. “People with impaired awareness of hypoglycemia may need to wear an additional monitor.”

Previous research indicated that hypoglycemia speeds up heart rate and alters heart rate variability—the normal beat-to-beat variation in heartbeats.

The researchers tested the feasibility of detecting hypoglycemia using HealthPatch—a commercially available biosensor that measures heart rate—and a single-lead electrocardiogram (ECG).

During the study, the patch continuously measured the heart rate of at least 20 participants with Type 1 diabetes, who self-reported frequent impaired awareness of hypoglycemia.

The subjects wore the patch on their chests, as well as a continuous glucose meter, for five days while at home and kept documentation any time they recorded a blood sugar level below 70 milligrams per deciliter, which was verified by fingerstick measurement.

Wireless technology also transmitted heart rate data to a mobile electronic device. The research team then used an algorithm to determine various parameters of heart rate variability and conducted a primary analysis on 39 hypoglycemic events that occurred in 10 of the study’s volunteers. These parameters were calculated from two hours before an hypoglycemic event up to one hours after as six-minute windows with 33 percent overlap.

In 28 low blood sugar events, the algorithm detected clear patterns of change in heart rate variability at the start of hypoglycemia. According to the researchers, the changes correspond with an activated sympathetic nervous system and suppressed activity of the parasympathetic nervous system, which occurs at the beginning of low blood sugar.

“Timely detection of impending hypoglycemia is critical to avoid severe, potentially life-threatening hypoglycemia,” Olde Bekkink said. “Our proof-of-principle study found that measuring heart rate variability using a wearable device in an outpatient setting seems promising for alerting to upcoming hypoglycemia.”

The researchers will now refine the algorithm to increase its accuracy and precision before the biosensor is used in daily practice for patients with Type 1 diabetes. They then plan to translate the data into an audiovisual hypoglycemia alert that could be sent directly to a mobile device.     

Results of the preliminary study were presented on March 17 at the ENDO 2018, the Endocrine society’s 100th annual meeting in Chicago.