Quantitative evaluation of diabetic autonomic neuropathy by using heart rate variations--determination of the normal range for the diagnosis of autonomic neuropathy.

Heart rate (HR) variations--in supine resting position, during deep breathing and on standing--were measured in 162 healthy subjects and 168 diabetics by use of an instantaneous-HR-change continuous recorder. As indices of HR variations, the standard deviation of the HR at rest (SD of HR), the mean difference between maximal and minimal HR during deep breathing (delta I-E) and the HR increase on standing (delta HR) were determined. In healthy subjects, the values for each test declined with age and the log-transformed data fitted the linear regression. The 90% confidence limits were calculated for the normal range and the values below normal range were defined as abnormal. In diabetics, the incidence of abnormal response were 19% in the SD of HR, 38% in the delta I-E and 22% in the delta HR. The delta I-E was the most sensitive index for the autonomic neuropathy. The delta HR was considered to be able to detect the different mechanisms of neural reflexes because of the poor correlation between the delta HR and the respiratory HR variations. The present studies suggested that delta I-E and delta HR should be measured at the same time to evaluate the autonomic neuropathy.