Economy smart watch fails to accurately monitor blood glucose among healthy adults

Monitoring and maintenance of blood glucose (BG) concentrations is of critical importance to individuals with diabetes mellitus. However, this often requires multiple finger-sticks and a glucometer, or the use of a prescription continuous glucose monitor (CGM). Recently, some smart watches have become available which claim to non-invasively monitor BG. This should not be confused with watches that pair with CGMs. The purpose of this study was to assess whether the economy smart watches were capable of detecting BG changes among healthy individuals. Currently three participants have completed this study. Healthy young adults reported to the lab after a 4-6 hour fast to perform an oral glucose tolerance test (OGTT). The participants wore a Dexcom G7 CGM which is FDA approved and frequently prescribed for the monitoring of BG concentrations. In tandem, they wore the smart watch. Over the course of two hours, BG measurements were taken on both devices so that the changes could be compared. Results: During the OGTT there was a significant difference in the two devices measurements of BG over time (Λ=0.04, F=50.95, p=0.02). Due to currently low sample size, the difference across timepoints does not appear significant for either the CGM (F=7.83, p=0.09) or the smart watch (F=0.42, p=0.63). While the study is ongoing, it is already becoming clear that the smart watch is not accurate in its assessment of BG, and thus should not be endorsed for use in guiding any medical decision making.