Diabetes Care, Vol 16, Issue 5 789-795, Copyright © 1993 by American Diabetes Association
Effect of aldose reductase inhibitor (tolrestat) on urinary albumin excretion rate and glomerular filtration rate in IDDM subjects with nephropathy
N Passariello, J Sepe, G Marrazzo, A De Cicco, A Peluso, MC Pisano, S Sgambato, P Tesauro and F D'Onofrio
Institute of General Medicine, Therapy and Metabolic Disease, 1st Faculty of Medicine and Surgery, University of Naples, Italy.
OBJECTIVE--To explore the possible link between diabetic nephropathy and
the enhanced activity of the polyol pathway, known to occur in IDDM
subjects. RESEARCH DESIGN AND METHODS--We studied the effects of the aldose
reductase inhibitor tolrestat (200 mg/day) on urinary albumin excretion
rate and glomerular filtration rate in 20 IDDM patients with diabetic
nephropathy. RESULTS--Six months of placebo treatment produced no
significant changes in glomerular filtration rate, urinary albumin
excretion rate, and renal plasma flow. Consequently, filtration fraction
remained unchanged. During tolrestat treatment, glomerular filtration rate
decreased from the basal value of 156 +/- 14 ml.min-1.1.73 m2 to 142 +/-
13.7 ml.min-1.1.73 m2 (P < 0.001) at 2 mo; 128 +/- 12.4 ml.min-1.1.73 m2
(P < 0.001) at 4 mo; and 123.7 +/- 13.0 ml.min-1.1.73 m2 at 6 mo. A
significant decrease of urinary albumin excretion rate was observed during
the trial (basal values 219 +/- 32.5 vs. 196.9 +/- 28.5 micrograms/min at 2
mo [P < 0.05]; 171.6 +/- 25.5 micrograms/min at 4 mo [P < 0.001]; and
58.6 +/- 19.3 micrograms/min at 6 mo [P < 0.001]). No significant change
in renal plasma flow was seen during tolrestat treatment. Filtration
fraction significantly decreased in the tolrestat group from the basal
value of 0.23 +/- 0.02 to 0.21 +/- 0.01 at 2 mo (P < 0.005); 0.18 +/-
0.02 at 4 mo (P < 0.001); and 0.17 +/- 0.02 at 6 mo (P < 0.001).
CONCLUSIONS--The polyol pathway is implicated in hemodynamic changes
associated with early diabetic nephropathy, and aldose reductase treatment
can positively influence these parameters.