Beat-to-beat blood pressure response in asymptomatic IDDM subjects

Nine insulin-dependent diabetic (IDDM) patients (aged 25-37 yr) with no symptoms of autonomic neuropathy and 15 healthy control subjects (aged 26-39 yr) were studied at rest and during tests of Valsalva maneuver, deep breathing, cold pressor, and postural change from sitting to standing. Continuous (beat-to-beat) measures were taken of heart rate, systolic blood pressure, diastolic blood pressure, and skin conductance. The diabetic patients were differentiated from the control group by the following: less variability in diastolic blood pressure during deep breathing, failure to exhibit diastolic blood pressure decreases during recovery from a cold pressor stimulus, a flatter blood pressure response pattern when changing from sitting to standing, and a smaller standing ratio (maximum/minimum) for R-R interval. Among the patients, age was negatively correlated with systolic and diastolic standing ratios and diastolic blood pressure variability during deep breathing. By use of the tracking cuff, a method of continuously recording blood pressure noninvasively, we have been able to assess subtle blood pressure changes, thereby revealing signs of sympathetic dysfunction in a group of relatively young diabetic patients with no symptoms of neuropathy. The tracking-cuff method of recording blood pressure has potential in further research on autonomic functioning in diabetic patients.