Peripheral Hemodynamics Estimation Using the Photoplethysmography Method.

Diabetes is known to reduce blood circulation in capillaries and arterioles; however, no devices can easily measure this on a daily basis. In this study, we developed a tool for measuring finger photoplethysmograms using green light and near-infrared LEDs. Thereafter, photoplethysmography was conducted on 25 inpatients/outpatients with diabetes and 21 adult males and females who had not been diagnosed with or treated for diabetes, hypertension, or cardiovascular disease (control group). In patients with diabetes, the inverse full width at half-maximum velocity plethysmogram tended to be smaller than that in the control group, and the delay in the green light a-wave peak relative to the near-infrared light a-wave peak in the acceleration plethysmogram was significantly increased. The results suggest that peripheral hemodynamics can be easily estimated at home using a photoplethysmography device mounted on a ring-wearable device.