Results: SDNN (Standard deviation of all normal sinus R-R intervals), ASDNN (The mean of the standard deviation of all normal sinus R-R intervals for all 5-minute segments of the entire recording), SDANN (Standard deviation of the averaged normal sinus R-R intervals for all 5 minute segments of the entire recording), RMSSD (The root mean square of the difference between the coupling intervals of adjacent R-R intervals) are lower in diabetes mellitus participants than normal.