Diabetic alteration of cardiac vago-sympathetic modulation assessed with tone-entropy analysis

No clear evidence of diabetic alteration of cardiac sympatho-vagal balance has been reported to date. We assessed heart rate variability of diabetic patients with the tone-entropy analysis that has been published elsewhere (Oida et al. 1997). Tone reflects the cardiac vago-sympathetic balance and entropy the total autonomic efferent activity. Diabetic influence on tone and entropy was examined in two groups of patients (38-52 years and 60-69 year, total 106) stratified according to the occurrence of impaired glucose tolerance or diabetes mellitus. Ten healthy middle-aged volunteers were also examined as a reference. Electrocardiographic data were collected at rest for 10 min. Tone increased and entropy decreased significantly with severity of diabetic disorders. The alterations were depicted as a curvi-linear relation in tone-entropy space, which superimposed adequately on the standard tone-entropy values obtained in a pharmacological experiment. The results demonstrate that the vago-sympathetic balance is altered with diabetic disorders: vagal predominance is impaired significantly in proportion to a withdrawal of total autonomic efferent activity.