24-HOUR MEAN LEVEL AND VARIABILITY OF BLOOD-PRESSURE AND HEART-RATE IN NORMOTENSIVE PATIENTS WITH INSULIN-DEPENDENT DIABETES-MELLITUS

This prospective study was designed: 1-degrees to determine both the mean level and the intrinsic variability of blood pressure (BP) and heart rate (HR) in normotensive patients with insulin-dependent diabetes mellitus (IDDM), by using a non ambulatory recorder; 2-degrees to look for a relationship between these parameters and the indices of diabetic target-organ damage. The patient group consisted of 21 subjects with IDDM (6 females, 15 males), aged 19 to 70 years, who were normotensive according to WHO criteria. The duration of the diabetes ranged from 1.5 to 32 years. A control group of 17 age and sex-matched normal volunteers was also examined. Each subject underwent a 24 h non ambulatory BP recording, a 2-dimensional echocardiography and a pulsed doppler examination; furthermore, an index of autonomic nervous system dysfunction was established, as well as an index of microangiopathy. Twenty-four hour BP and HR mean levels appeared to be slightly higher in IDDM patients than in control group, but the difference was significant for night SBP and 24 h DBP only. No difference was found with regard to BP and HR absolute variabilities; the relative variability of night DBP was slightly lower in IDDM group (p < 0.05). A loss of nocturnal decline in BP was noted in 2 control subjects and in 9 IDDM patients: 8 out of these IDDM patients had an autonomic dysfunction. An abnormal HR circadian pattern was seen in 1 control and in 2 IDDM subjects. The left ventricular mass index was roughly similar in both groups, and was not related to BP level; the isovolumic relaxation time and the deceleration time were significantly higher in IDDM patients. The positive correlations we found between A/E ratio and 24 h SBP, as well as between autonomic dysfunction index and night HR were age-dependent. By contrast, night DBP was related to microalbuminuria excretion rate, irrespectively to age.