Increased blood pressure variability during 24h blood pressure monitoring as an early sign of autonomic dysfunction in non-insulin-dependent diabetics.

To evaluate the presence of early autonomic dysfunction in non-insulin-dependent diabetics we examined 24h control of blood pressure (1/4 hourly readings day and 1/2 hourly at night, using TM 2420) in 20 non-insulin-dependent diabetics, controlled only on diet or oral hypoglycaemics and 20 age/sex/BP matched non-diabetics selected from a random population survey. The two groups were aged 52 +/- 9 years and 53 +/- 8 years, respectively. Both groups included normotensives and mild hypertensives in equal numbers but none was on antihypertensive treatment. The groups were well matched for daytime systolic blood pressure (SBP; 132.2 +/- 11.4 vs. 131.2 +/- 10.3) and diastolic blood pressure (DBP; 82.1 +/- 8.3 vs. 81.1 +/- 7.0). The diabetics had a significantly greater heart rate (HR) both during the day (79.6 +/- 9.5 vs. 72.3 +/- 8.8: P = 0.015) and during sleep (67.7 +/- 6.8 vs. 62.5 +/- 8.9). There was increased BP variability in the diabetics during the day (standard deviation of SBP; 16.9 +/- 6.2 vs. 13.3 +/- 4.7: P < 0.05) but the difference for DBP variability was not significant. The day-night difference for SBP, DBP, HR and HR variability was the same in both groups. We conclude that in these patients there was evidence for an alteration in BP variability (which may reflect baroreflex insensitivity) at a stage where there was no alteration in day-night rhythms of BP or HR. The increased HR both at day and night may also reflect baroreflex dysfunction and/or sympathovagal imbalance.(ABSTRACT TRUNCATED AT 250 WORDS)