Diabetes Care, Vol 20, Issue 8 1329-1333, Copyright © 1997 by American Diabetes Association
Glomerular hyperfiltration is associated with blood pressure abnormalities in normotensive normoalbuminuric IDDM patients
M Pecis, MJ Azevedo and JL Gross
Endocrine Unit, Hospital de Clinicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
OBJECTIVE: To analyze the blood pressure patterns in normoalbuminuric IDDM
patients with glomerular hyperfiltration. RESEARCH DESIGN AND METHODS: A
controlled cross-sectional study of 38 normotensive normoalbuminuric
(urinary albumin excretion rate < 20 micrograms/min) IDDM patients (18
hyperfiltering [glomerular filtration rate > 134 ml.min-1 1.73 m-2] and
20 normofiltering) and 20 normal individuals matched for age, sex, and BMI
was performed. The 24-h ambulatory blood pressure was monitored using an
auscultatory technique (Pressurometer IV, Del Mar Avionics), the glomerular
filtration rate was measured by 51Cr-labeled EDTA method, extracellular
volume by the distribution volume of 51Cr-labeled EDTA, and the 24-h
urinary albumin excretion rate by radioimmunoassay. RESULTS: Mean nocturnal
diastolic blood pressure was higher in hyperfiltering IDDM patients (70.4
+/- mmHg), when compared with the control group (65.1 +/- 5.3 mmHg, P =
0.04). Diastolic blood pressure night:day ratio was higher in
hyperfiltering IDDM patients (92.0 +/- 8.6%), when compared with
normofiltering IDDM patients (85.9 +/- 4.8%) and control subjects (87.0 +/-
6.8%, P = 0.02). In IDDM patients, the glomerular filtration rate
significantly correlated with the diastolic blood pressure night:day ratio
(r = 0.5, P = 0.002), extracellular volume (r = 0.04, P = 0.002), and HbA1
(r = 0.3, P = 0.03). In stepwise multiple regression analysis, factors
associated with glomerular filtration rate were diastolic blood pressure
night:day ratio, extracellular volume, and HbA1 (adjusted r2 = 0.27, P =
0.003). CONCLUSIONS: Glomerular hyperfiltration is associated with higher
nocturnal diastolic blood pressure and with a blunted nocturnal decrease in
diastolic blood pressure levels in normotensive and normoalbuminuric IDDM
patients.