A Noninvasive Blood Glucose Estimation System Using Dual-Channel PPGs and Pulse-Arrival Velocity

Diabetes is a chronic metabolic disorder that requires individuals with diabetes to perform 'finger stick blood sugar tests' multiple times a day. This invasive method is not capable of continuously monitoring a diabetic patient's blood glucose levels and can be painful and inconvenient in the long term. In our study, we developed a noninvasive blood glucose estimation method using dual-channel photoplethysmography (PPG) combined with pulse arrival velocity (PAV). The dual-channel PPG was chosen based on the advantages of 530 nm PPG in blood flow measurement and 1550 nm infrared light in blood glucose concentration detection. In addition to testing various amplitude features in PPG at different fiducial points (systolic peak, dicrotic notch, and diastolic peak), we also examined the amplitude ratio between the two PPG channels (530 nm green-light PPG and 1550 nm infrared PPG), as well as PAV, for noninvasive blood glucose estimation. In this study, we recruited 18 healthy subjects (14 males and four females; aged 29.4 ± 7.87 years old). The oral glucose tolerance test (OGTT) experiment was conducted on each participant to manipulate the blood glucose level. Each parameter for blood glucose estimation was examined using partial F-test to assess its impact on blood glucose estimation. We found that combining the amplitude ratio of the dual-channel PPG with PAV resulted in the best blood glucose estimation results, with estimation results falling within Zone A in the Clarke error grid analysis (CEGA) with a 100% success rate, and the root-mean-square-error (RMSE) being 7.46 ± 2.43 mg/dL.