IMPACT OF ARTERIAL BLOOD-PRESSURE AND ALBUMINURIA ON THE PROGRESSION OF DIABETIC NEPHROPATHY IN IDDM PATIENTS

To evaluate the impact of systemic blood pressure and albuminuria on t he progression of diabetic nephropathy, we followed 41 IDDM patients w ith persistent albuminuria (> 300 mg/24 h) by measuring glomerular fil tration rate (Cr-51-EDTA technique), blood pressure, and albuminuria. None of the patients were taking drugs other than insulin. Arterial bl ood pressure, albuminuria, and blood glucose were measured four to eig ht times/yr, whereas glomerular filtration rate was determined twice y early. During the median investigation period of 36 (15-66) mo, glomer ular filtration rate decreased from 102 +/- 23 to 83 +/- 27 ml . min-1 . 1.73 m- 2(P < 0.001), albuminuria increased from 633 to 1435 mug/mi n (P < 0.001), and blood pressure rose from 133/85 +/- 10/9 to 149/93 +/- 8/11 mmHg (P < 0.001). Univariate analysis revealed a significant correlation between the rates of decline in glomerular filtration rate and diastolic blood pressure (r = 0.52, P < 0.01) and glomerular filt ration rate and albuminuria (r = 0.34, P < 0.02). But stepwise multipl e linear regression analysis only showed a significant correlation bet ween the rate of decline in glomerular filtration rate and diastolic b lood pressure (P < 0.01). In patients with diastolic blood pressure be low the mean value of 89 mmHg, stepwise multiple regression analysis s howed that albuminuria and not blood pressure was correlated significa ntly with rate of decline in glomerular filtration rate. Patients were stratified by average value of diastolic blood pressure measured duri ng the investigation period. Patients in the lowest tertile had a rate of decline in glomerular filtration rate of 4.3 +/- 4 ml . min-1 . yr -1 compared with the middle and the highest tertiles of 7.7 +/- 5 and 10.1 +/- 5 ml . min-1 . yr-1, respectively (P < 0.01). The average dia stolic blood pressure in the three groups was 81, 89, and 98 mmHg, res pectively. This study suggests that systemic blood pressure elevation and albuminuria accelerate the progression of diabetic nephropathy. Th e latter progression promoter seems only to play a role in patients wi th normotension (diastolic blood pressure < 89 mmHg).