Aim: The aim of this study was to emphasize two different points in our
work: 1) The well known importance of (subclinical) postural
hypotension and reduced heart rate variability as (early) markers of
autonomic neuropathy; 2) and the more controversial influence of
diabetic control in their worsening. Methods: Two standard
cardiovascular response tests (heart rate variability by respiration
and orthostatic blood pressure changes) were carried out on 93 diabetic
patients with prolonged QT interval in order to determine cardiac
dysautonomy. QT segment duration was measured on electrocardiography
recordings. Patients with HbA1c levels below 7 were considered as
well-controlled diabetics. A cut off of 5 years was selected for the
known duration of diabetes. The relations between cardiac autonomic
neuropathy and diabetic control and the known duration of diabetes were
determined. Results: The mean values for the known duration of diabetes
and HbA1c level were 10±7.23 years and 9.5±2.3 mg/dl
respectively. Median QTc differences, postural change in the systolic
blood pressure, and changes of heart rate by respiration were 0.62 sec,
20 mmHg, and 6 beat/min, respectively. There was no difference in QTc
values with respect to diabetes control but QTc values were
significantly different with regard to the known duration of diabetes.
Blood pressure variations with standing were significantly related to
control as well as the known duration of diabetes. Variability of
hearth rate with respiration on the other hand was significantly
related to the duration but not to the control of diabetes. QTc showed
a significant correlation with the known duration of diabetes, postural
blood pressure changes, and heart rate variability with respiration.
Conclusion: Clinician's should be more alert for the signs of autonomic
neuropathy, especially in patients with a history of diabetes for more
than five years. Special attention should be given to postural blood
pressure changes and heart rate variability with respiration
