Diabetes Care, Vol 20, Issue 3 429-432, Copyright © 1997 by American Diabetes Association
Elevated ambulatory blood pressure in microalbuminuric IDDM patients is inversely associated with renal plasma flow. A compensatory mechanism?
PL Poulsen, B Juhl, E Ebbehoj, F Klein, C Christiansen and CE Mogensen
Department of Medicine M (Diabetes & Endocrinology), Aarhus Kommunehospital, Denmark.
OBJECTIVE: To evaluate the relationship between renal function, ambulatory
blood pressure (AMBP), and glycemic control in microalbuminuric IDDM
patients compared with normoalbuminuric patients. RESEARCH DESIGN AND
METHODS: Nineteen male patients (age 33 +/- 6 years) with slight
microalbuminuria (UAE 20-70 micrograms/min) were compared with 19
normoalbuminuric (UAE < 15 micrograms/min) age-matched (33 +/- 6 years)
male patients. Through constant infusion technique, 125I-iothalamate marked
the glomerular filtration rate (GFR), and 131I-hippuran marked effective
renal plasma flow (RPF). AMBP was measured by oscillometric technique
(Spacelabs 90202). RESULTS: The microalbuminuric group had higher daytime
systolic AMBP (132 +/- 11 vs. 125 +/- 7 mmHg, P < 0.05) and a poorer
glycemic control (HbA1c 9.5 +/- 1.5 vs. 8.2 +/- 1.3%, P < 0.01). GFR
(135 +/- 22 and 135 +/- 17 ml/min) and RPF (598 +/- 112 and 542 +/- 98
ml/min) were similar in the two groups. In the microalbuminuric group,
daytime systolic AMBP was inversely correlated to both RPF (r = -0.77, P
< 0.005) and GFR (r = -0.53, P = 0.02). HbA1c and GFR correlated
positively in the microalbuminuric group (r = 0.47, P < 0.04). In
contrast, the normoalbuminuric patients exhibited no such associations.
CONCLUSIONS: IDDM patients with moderate microalbuminuria have elevated
AMBP and a strong negative association between AMBP and RPF. This leaves
several possibilities of interpretation. Primary blood pressure increase
(of unknown origin) may induce morphological changes leading to reduction
in renal function. Alternatively, blood pressure increase early in the
course of incipient nephropathy may represent a compensatory mechanism,
initially aiming at preservation of renal function, but later becoming
maladaptive.