Glycemic control, hand activity, and complexity of biological signals in diabetes mellitus

Abstract

Both glycemic control and handgrip strength affect microvascular function. Multiscale entropy (MSE) of photoplethysmographic (PPG) pulse amplitudes may differ by diabetes status and hand activity. Of a middle-to-old aged and right-handed cohort without clinical cardiovascular disease, we controlled age, sex, and weight to select the unaffected (no type 2 diabetes, n = 36), the wellcontrolled diabetes (HbA1c < 8%, n = 22), and the poorly controlled diabetes (HbA1c ≥ 8%, n = 22) groups. MSEs were calculated fromconsecutive 1,500 PPG pulse amplitudes of bilateral index fingertips. The small-, medium-, and large-scale MSEs were defined as the average of scale 1 (MSE1), scales 2–4 (MSE2–4), and scales 5–10 (MSE5–10), respectively. Intra- and intergroups were compared by one- and two-sample t-tests, respectively. Thedominant handMSE5–10 was lower in the poorly controlled diabetes group than the well-controlled diabetes and the unaffected (1.28 versus 1.52 and 1.56, p = 0.019 and 0.001, resp.) groups, whereas the nondominant hand MSE5–10 was lower in the well- and poorly controlled diabetes groups than the unaffected group (1.35 and 1.29 versus 1.58, p = 0.008 and 0.005, resp.). The MSE1 of dominant hand was higher than that of nondominant hand in the well-controlled diabetes (1.35 versus 1.10, p = 0.048). In conclusion, diabetes status and hand dominance may affect the MSE of PPG pulse amplitudes.