GLOMERULAR HYPERFILTRATION IS ASSOCIATED WITH BLOOD-PRESSURE ABNORMALITIES IN NORMOTENSIVE NORMOALBUMINURIC IDDM PATIENTS

OBJECTIVE - To analyze the blood pressure patterns in normoalbuminuric IDDM patients with glomerular hyperfiltration. RESEARCH DESIGN AND ME THODS - A controlled cross-sectional study of 38 normotensive normoalb uminuric (urinary albumin excretion rate <20 mu g/min) IDDM patients ( 18 hyperfiltering [glomerular filtration rate > 134 ml . min(-1) . 1.7 3 m(-2)] and 20 normofiltering) and 20 normal individuals matched for age, sex, and BMI was performed. The 24-h ambulatory blood pressure wa s monitored using an auscultatory technique (Pressurometer IV, Del Mar Avionics), the glomerular filtration rate was measured by Cr-51-label ed EDTA method, extracellular volume by the distribution volume of Cr- 51-labeled EDTA, and the 24-h urinary albumin excretion rate by radioi mmunoassay. RESULTS - Mean nocturnal diastolic blood pressure was high er in hyperfiltering IDDM patients (70.4 +/- 7.8 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 (9 2.0 +/- 8.6%), when compared with normofiltering IDDM patients (85.9 /- 4.8%) and control subjects (87.0 +/- 6.8%, P = 0.02). In IDDM patie nts, the glomerular filtration rate significantly correlated with the diastolic blood pressure night:day ratio (r = 0.5, P = 0.002), extrace llular volume (r = 0.4, P = 0.002), and HbA(1) (r = 0.3, P = 0.03). In stepwise multiple regression analysis, factors associated with glomer ular filtration rate were diastolic blood pressure night:day ratio, ex tracellular volume, and HbA(1) (adjusted r(2) = 0.27, P = 0.003). CONC LUSIONS - Glomerular hyperfiltration is associated with higher nocturn al diastolic blood pressure and with a blunted nocturnal decrease in d iastolic blood pressure levels in normotensive and normoalbuminuric ID DM patients.