Use of runs test to assess cardiovascular autonomic function in diabetic subjects

We suggest a simple, noninvasive method to assess the autonomic function in diabetic subjects. The method requires only a monitoring of heart rate (HR) with subjects in the sitting position.

Sixty diabetic subjects, 44 men and 16 women, between 20-80 years of age, were recruited, chronologically, for this study. Subjects treated for high blood pressure were not included. Their autonomic function was assessed by the total score of five classical cardiovascular function tests. In the same subjects and in 44 healthy subjects, blood pressure and HR were determined from beat to beat by the Finapres system with subjects in the sitting position. We examined the randomness of the HR changes by calculating the zeta statistic of the runs test on 1,000 successive HR readings (the zeta value is low if the HR changes are random). When the HR changes are random, we consider that the autonomic control of HR is impaired.

The zeta values of HR changes were significantly lower in diabetic subjects compared with normal subjects (2.98 +/- 0.97 vs. 3.54 +/- 0.97, P < 0.004). In diabetic subjects, the zeta value was closely correlated to the total score of disautonomy (r = -0.66, P < 0.0001, after correction for age effect) and to the office systolic blood pressure (r = -0.43, P < 0.001).

The zeta value of HR changes might be a marker of the autonomic function in diabetic subjects.