A new device has been developed for non-invasive assessment of glucose, endothelial vascular function, and other body parameters, which includes an optical circuit configured to detect several photoplethysmography (PPG) signals. A PPG signal includes a first spectral response obtained from light reflected around a first wavelength, and a second PPG signal includes a second spectral response obtained from light reflected around a second wavelength from the tissue of the user. This technology was investigated in a pilot study, which served the primary purpose to improve the underlying algorithm used to extract the glucose concentration from the obtained readings.
Twelve patients participated in the trial (5 female, 7 male, 5 Type 1, 7 Type 2 diabetes, age: 57±18 yrs). The received a standardized meal and glucose was measured at 11 time-points over a period of 3 h. YSI 2300Statplus served as reference method for the non-invasive readings.
The device worked well in all patients with one exception (male patient with very thick skin). All results were included into the analysis. The observed measurement range was 59 mg/dL to 371 mg/dL. Mean absolute relative difference over the entire data set (n = 104) was 8.0 %. In the consensus error grid, 98 % of the results were in zone A and 1.9 % were found in zone B.
The prototypes tested with a new and promising non-invasive glucose assessment technology showed to reliably and accurately measure glucose levels in this first pilot study.