Relationship between autonomic neuropathy, 24-h blood pressure profile, and nephropathy in normotensive IDDM patients.
OBJECTIVE
To evaluate the relationship between autonomic neuropathy, nephropathy, and 24-h blood pressure (BP) pattern in insulin-dependent diabetes mellitus (IDDM).


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.
Spallone
V
V
Department of Internal Medicine, Endocrinology, Tor Vergata University, Rome, Italy.
Gambardella
S
S
Maiello
M R
MR
Barini
A
A
Frontoni
S
S
Menzinger
G
G
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D001794:Blood Pressure; D003404:Creatinine / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D003928:Diabetic Nephropathies / Q000097:blood / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000097:blood / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000097:blood / Q000503:physiopathology; D003971:Diastole; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D012016:Reference Values; D012044:Regression Analysis; D012119:Respiration; D013599:Systole; D014636:Valsalva Maneuver
D003404:Creatinine