Fig. 1

Plots comparing heart rate variability indices during hemodialysis among the four groups. a VLF, b LF, c HF, d TP, e Var, f LF/HF. red solid line FPG(+), n =  65; blue solid line FPG(-), n = 110; red dashed line FPG(+)/MetS(+), n = 54; red dotted line FPG(+)/MetS(-), n = 11; blue dashed line FPG(-)/MetS(+), n = 37; blue dotted line FPG(-)/MetS(-), n = 73. HRV-1, -2, and -3 were HRV measured at initial, middle, and late phase of the HD session, respectively. #, ##, ### denote p ≤ 0.05, ≤0.01, ≤0.001, respectively, between FPG(+) and FGP(-) groups. *, **, *** denote p ≤ 0.05, ≤0.01, ≤0.001, respectively, between two subgroups. Blue and red arrow lines respectively denote the trend of serial change of HRV in FPG(-) and FPG(+) groups. ^$ denotes p ≤ 0.001. Units: Ln(ms2) in VLF, LF, HF, TP, and Var; Ln(ratio) in LF/HF ratio. FPG fasting plasma glucose, HF high frequency; HRV heart rate variability, LF low frequency, MetS metabolic syndrome, TP total power, Var variance of the R-R intervals, VLF very low frequency