“…Blood glucose concentration measurement methods can be divided into non-invasive methods [ 4 , 5 , 6 ] and invasive methods [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. While invasive methods do not provide painless measurements, these methods can avoid individual patient differences (including race, skin color, skin composition, skin thickness, and complex blood components) and increase the reliability of clinical diagnosis.…”