Ambulatory blood pressure and heart rate in diabetic patients: an assessment of autonomic function.

In order to examine the physiological variation in blood pressure and heart rate that occurs during normal activities in patients with diabetes, 24-h profiles were constructed from continuous ambulatory recordings. Isometric and dynamic tests were also performed. The patients were subdivided into 25 uncomplicated cases, 11 with peripheral neuropathy and 6 with autonomic neuropathy. These were compared with a 'control' group of 22 normal subjects. Abnormal 24-h blood pressure profiles were found particularly in the patients with autonomic neuropathy. This group had attenuation or reversal of the usual diurnal rhythm, blood pressure often rising during the night and falling in the early morning. Diurnal heart rate variation was reduced in all three groups of patients. Blood pressure responses to both forms of exercise were also significantly reduced in the autonomic neuropathy group (maximum change in systolic blood pressure during isometric exercise was 10 +/- 4 mmHg vs 36 +/- 3 mmHg in the control group, p less than 0.003). Patients with peripheral neuropathy also had some impairment of exercise-induced blood pressure changes, but to a lesser degree.