RELATIONSHIP BETWEEN AUTONOMIC DYSFUNCTION AND BP VARIABILITY IN SUBJECTS WITH DIABETES-MELLITUS

Autonomic vagal heart rate (HR) control, office BP and ambulatory BP w ere examined in 54 diabetic subjects, aged 63 +/- 6 years. Sixteen sub jects were insulin-dependent. The HR response to deep breathing (the b radypnoea test) was used to evaluate the vagal HR control, and ambulat ory BP was determined by the Spacelabs 5200 system (one determination every 15 minutes, for 24 hours). Twenty-seven subjects had normal offi ce BP (SBP less-than-or-equal-to 140 mmHg and DBP 90 mmHg), seven had established hypertension (SBP 160 mmHg and DBP greater-than-or-equal-t o 95 mmHg) and 30 were borderline hypertensives. Over the total group, office systolic/diastolic BP (mean +/- SD) was 142 +/- 20/85 +/- 10 m mg. Systolic/diastolic ambulatory BP was 123 +/- 13/77 +/- 10 mmHg and ambulatory HR was 70 +/- 8 beats/min. Because of the small age range of our subjects, the HR score was not correlated with age (r = 0.19, N S). The HR score was not correlated with the levels of office and ambu latory pressures. In contrast, it was significantly correlated with th e variability of ambulatory SBP, whether the variability was defined b y the pressure standard deviation, or by the ratio SD/mean value (r = 0.40, P = 0.005 and r = 0.33, P < 0.017, respectively). We suggest tha t an impairment of the autonomic control in diabetics might induce an increase in variability of SBP. BP variability might play a role in th e cardiovascular complications observed in diabetics.