Wearable device and method for determining glycated hemoglobin level

A wearable device for determining a glycated hemoglobin level, the wearable device comprising:

• at least three radiation sources configured to irradiate biological tissues of a user with radiation of at least three different wavelengths;
• at least two radiation detectors, each of the at least two radiation detectors being configured to detect photoplethysmographic (PPG) signals representing the radiation of the at least three different wavelengths backscattered by the biological tissues;
• and
• at least one processor configured to:
• activate the at least three radiation sources and the at least two radiation detectors in pairs of measurement channels for the PPG signals;
• sequentially detect the PPG signals through each of the measurement channels by switching the measurement channels during a measurement cycle of the PPG signals;
• form, from the detected PPG signals, a dataset including a time series of values of the PPG signals relative to the at least three different wavelengths and relative to lengths of the measurement channels, and which defines an absorption of the PPG signals by the biological tissues of the user;
• generate a pre-processed dataset by carrying out a pre-processing of the dataset;
• and
• determine a glycated hemoglobin level based on the pre-processed dataset by a pre-trained machine learning model.