Diurnal variations in blood pressure, heart rate and pressure rate product were analyzed in 68 hospitalized diabetics (male 42, female 26) and 33 hospitalized controls (male 21, female 12) to investigate the influence of diabetic autonomic neuropathy on hemodynamics. The severity of autonomic damage was assessed by measuring the variabilities in R-R intervals of 100 consecutive heart beats in ECGs during quiet and deep breathing in the supine position and with the Schellong test. According to the results, the diabetics were divided into three groups: Normal ANS (31 patients without diabetic autonomic neuropathy), Abnormal PS (27 patients with parasympathetic damage alone) and Abnormal PS+S (10 patients with both parasympathetic and sympathetic damage). The blood pressure and heart rate of all subjects were recorded for 24 hours under near-basal conditions using an ambulatory blood pressure recording device (Pressurometer® Ⅱ, Del Mar Avionics, USA). The patterns of diurnal variations and the diurnal variabilities in blood pressure, heart rate and pressure rate product were analyzed in 22 control, 21 normal ANS, 20 abnormal PS and 10 abnormal PS+S patients. The effects of atropine sulfate (2.0mg daily, p.o.) were also studied in 11 control, 10 normal ANS and 11 abnormal PS patients to determine the effect of parasympathetic nerve damage on the variations. Hourly mean heart rates during the daytime and mean 24-hour heart rates were not different among the groups. However, with the progress of autonomic neuropathy, there was a significant reduction in the diurnal variation in heart rates, with greater mean night heart rates and greater hourly minimum mean heart rates. On the other hand, with the progress of autonomic neuropathy, there was a significant increase in the diurnal variation in the systolic blood pressure. However, diastolic blood pressure varied to the same extent regardless of the severity of autonomic nerve damage. The diabetics with autonomic neuropathy had significantly greater hourly mean and mean 24-hour systolic and diastolic blood pressure, and pressure rate product. The diurnal variation in the pressure rate product was similar to the heart rate results. Indices of the diurnal variations in heart rate and systolic blood pressure in controls and normal ANS patients approached those of abnormal PS patients after atropine sulfate administration. This result suggests that damage to the cardiac parasympathetic nerve plays a major role in the changes in the diurnal variations in heart rate and systolic blood pressure observed in diabetics.
24-hour blood pressure monitoring
diabetic autonomic neuropathy
R-R interval variation