Continuous glucose monitors (CGMs) are generally recognized as very useful tools for people with diabetes, particularly because they can warn of hypoglycemia early enough so that patients can treat their low blood sugar earlier and stay safer. CGMs are a particularly valuable tool for individuals who have hypoglycemia unawareness.

However, access to CGM technology (due to factors like cost and lack of insurance coverage) remains an issue for many people who may benefit from the product but simply cannot afford the financial burden.

Interestingly, some research indicates that heart rate variability trends are directly related to falling blood glucose levels. Earlier this year, a study evaluating the efficacy of heart rate monitoring for the detection of hypoglycemia was published in the journal Diabetes Care.

Study Design

The study authors explained that “changes in heart rate variability (HRV) occur at the initiation of hypoglycemia due to sympathetic nervous system activity.” As such, they set out to investigate whether a wearable heart rate monitor could serve as an effective alert of low blood glucose levels in patients with type 1 diabetes.

In this early “proof-of-principle” study, only 23 patients were enrolled and the study period only spanned for five days. Participants wore a device called VitalPatch that monitors several health parameters, including heart rate.

The researchers examined the heart rate data just prior to a recorded hypoglycemic event (defined as a blood glucose value below 70 mg/dL) as determined by a standard fingerstick blood glucose reading. A total of 66 hypoglycemic events were identified during the study period.

Study Outcomes

The analysis indicated that no change in HRV occurred in only 3% of cases. Heart rate variation patterns were observed for 82% of hypoglycemic events and were further categorized as “typical” and “atypical” HRV trends. The authors reported that “hypoglycemia caused a typical HRV pattern in 55% of the hypoglycemic events, [while] 27% showed an atypical pattern.” Also, patterns could not be classified for 15% of the hypoglycemic events.

Conclusions

This initial investigation demonstrated that heart rate variability patterns could be detected prior to a low blood glucose event.

The researchers concluded that “hypoglycemia causes early changes in HRV that can be detected by a wearable device. Measuring real-time HRV seems promising for early hypoglycemia detection.”

Additional investigations over a longer time period in a larger population will be necessary to confirm these findings and provide further information about the efficacy of this approach. If more promising data is uncovered, this research could potentially lead to the development of a non-invasive (and hopefully affordable) device for the early detection of hypoglycemia.

Read more about blood glucose monitoring, continuous glucose monitor (CGM), heart rate, Intensive management, low blood sugar (hypoglycemia).