Detection of Diabetic Neuropathy Using Blood Volume Ratio of Finger and Toe by PPG

Nerve conduction velocity (NCV) has been used as a standard method for diagnosing diabetic neuropathy. However, strong electric stimulus causes stress and pain. The purpose of this study is to suggest a simple screening method for detecting diabetic neuropathic foot caused from nerve damages in the legs. Photoplethysmography (PPG) and Laser Doppler (LD) were utilized to measure the blood volume changes and perfusions from fingers and toes. As a result of the PPG signal measurements, ratios of toe to finger obtained from the neuropathy group were significantly higher than those of the normal group (p <0.001). Sensitivities of the PPG method were found to be 98.0 % for both sides. Specificities were found to be 98.4 % for the left and 92.2% for the right side. The suggested PPG method is reliable, simple, low-cost, and noninvasive which could become an effective new screening tool for the early detection of diabetic neuropathic foot.