Abstract Body: The circadian patterns of blood pressure, including dipping and non-dipping profiles, constitute a risk factor for cardiovascular disease. Ambulatory blood pressure monitoring (ABPM) serves as the primary method for their identification. However, the ABPM device is costly and not suitable for large-scale population screening. Consequently, this study aimed to employ a S7 smartwacth (SKG Health Technologies, China) equipped with photoplethysmography(PPG) for continuous one day monitoring, utilizing the time series of pulse features to differentiate between various circadian patterns of blood pressure. Patients were excluded if they wore a smartwatch or had data recorded for under 20 hours. The study included 48 hospitalized diabetic patients who wore an S7 smartwatch and an ABPM device. Continuous pulse sequences were extracted from PPG signals via foot detection, and pulse characteristics were then assessed using time-domain or frequency-domain methods.
Heart rate, pulse width ratio, and pulse area ratio are employed as significant parameters to differentiate between dipper and non-dipper individuals. Dippers were defined as patients demonstrating a nocturnal blood pressure reduction exceeding 10% relative to their average daytime blood pressure, with ABPM serving as the gold standard for measurement. The findings indicated that the accuracy rate for distinguishing dippers from non-dippers using the photoplethysmography (PPG)-based method was 83.3%.The chi-square statistic of 14.4 indicates a strong correlation between the classifications obtained from the PPG-based method and the gold standard classifications derived from the ABPM method (P < 0.001).In conclusion, the continuous 24-hour monitoring of photoplethysmography using smartwatches represents a viable and reliable method for detecting circadian patterns in blood pressure, highlighting its significant potential for large-scale population screening.