Diabetes Care, Vol 17, Issue 6 578-584, Copyright © 1994 by American Diabetes Association
Relationship between autonomic neuropathy, 24-h blood pressure profile, and nephropathy in normotensive IDDM patients
V Spallone, S Gambardella, MR Maiello, A Barini, S Frontoni and G Menzinger
Department of Internal Medicine, Endocrinology, Tor Vergata University, Rome, Italy.
OBJECTIVE--To evaluate the relationship between autonomic neuropathy,
nephropathy, and 24-h blood pressure (BP) pattern in insulin-dependent
diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS--We studied 30
normotensive IDDM patients without overt nephropathy, divided into two
groups and matched for age, duration of diabetes, and HbA1, according to
the presence of cardiovascular autonomic neuropathy. We simultaneously
measured 24-h BP and urinary albumin excretion rate (UAE) on urine
collections timed overnight and at 2-h intervals during the day.
RESULTS--Mean day and night systolic and diastolic BP values did not
significantly differ between the groups. Mean night albuminuria was
significantly higher in patients with autonomic neuropathy than in those
without (61.4 +/- 104.6 [mean +/- SD] vs. 16 +/- 25.2 micrograms/min, P
< 0.04). The percentages day-night changes in systolic BP, diastolic BP,
and UAE were significantly lower in neuropathic patients (systolic BP: 2.4
+/- 7.7 vs. 9.6 +/- 4.2%, P < 0.001; diastolic BP: 8.4 +/- 6.9 vs. 15.5
+/- 5.4%, P < 0.002; UAE: -8 +/- 99.4 vs. 49.3 +/- 29.4%, P < 0.02)
and were inversely related to autonomic score, index of autonomic
neuropathy degree (r = -0.54, P < 0.002; r = -0.58, P < 0.001; and r
= -0.53, P < 0.005, respectively). In patients with autonomic
neuropathy, 2-h day periods and day and night UAE were more strongly
related, respectively, to mean 2-h day periods (r = 0.58, P < 0.0001),
day systolic BP (r = 0.67, P < 0.04), and night systolic BP (r = 0.69, P
< 0.04) than in patients without autonomic neuropathy (2-h day periods:
r = 0.32, P < 0.001; day: r = 0.37, NS; night: r = 0.35, NS).
CONCLUSIONS--Autonomic neuropathy in IDDM patients is associated with
reduced nocturnal falls in BP and UAE and with a stronger relationship of
UAE to systolic BP. We suggest a pathogenetic role of autonomic neuropathy
in the development of diabetic nephropathy through changes in nocturnal
glomerular function and by enhanced kidney vulnerability to hemodynamic
effects of BP.