RELATIONSHIP BETWEEN DIABETIC AUTONOMIC DYSFUNCTION AND HEART-RATE-VARIABILITY ASSESSED BY RECURRENCE PLOT

Beat-to-beat heart rate (HR) and blood pressure were measured by the F inapres system in 44 healthy and 64 diabetic subjects in the at-rest c ondition. Autonomic control in diabetic subjects was assessed by the E wing test. HR variability was explored by both linear and nonlinear me thods. Linear methods used HR standard deviation and power spectrum. T he percentage of the spectrum in the low frequencies was used to asses s the sympathetic tone of the autonomic control. The nonlinear method used the ''recurrence plot.'' This method explored long parallel subse quences in the HR time series. These sequences characterize the depend ence of the HR dynamics on initial values. The HR standard deviation w as reduced in the diabetic subjects compared with the healthy subjects (2.80 +/- 1.17 vs. 3.64 +/- 1.45 beats/min; P < 0.001). In the diabet ic subjects, the HR standard deviation and the percentage of the spect rum in the low frequencies showed no correlations with the Ewing score (P > 0.10). In contrast, the longest length index was very strongly c orrelated to the Ewing score (r = -0.60; P < 0.0001). The results sugg est that nonlinear methods might be powerful to explore the autonomic dysfunction in diabetic subjects.