Diabetes Care, Vol 20, Issue 3 286-289, Copyright © 1997 by American Diabetes Association
Stable glomerular filtration rate in normotensive IDDM patients with stable microalbuminuria. A 5-year prospective study
ER Mathiesen, B Feldt-Rasmussen, E Hommel, T Deckert and HH Parving
Steno Diabetes Center, Copenhagen, Denmark.
OBJECTIVE: To investigate the long-term course of glomerular filtration
rate (GFR) in IDDM patients with microalbuminuria in order to identify
patients with stable or declining kidney function over a 5-year study.
RESEARCH DESIGN AND METHODS: Forty normotensive (129 +/- 11/80 +/- 8 mmHg)
IDDM patients with persistent microalbuminuria (mean urinary albumin
excretion [UAE] 84 mg/24 h [range 30-300]) were followed prospectively for
5 years of clinical examinations that included the measurement of GFR
(51Cr-labeled EDTA clearance) at least once a year. The mean GFR at
baseline was 120 +/- 18 ml x min-1.1 x 73 m-2. RESULTS: Using multiple
regression analysis, the rate of decline in GFR was independently
correlated to onset of diabetic nephropathy (P < 0.001) and systolic
blood pressure (sBP) at baseline (P < 0.05). Increase in UAE was
correlated to the mean HbA1c during the observation period. Out of 40
patients, 14 progressed to diabetic nephropathy (UAE > 300 mg/24 h).
These patients had a significant reduction in GFR (mean -2.2 +/- 3.8 ml x
min-1 x year-1; P = 0.05), while GFR remained stable in the remaining 26
patients with nonprogressive microalbuminuria (change in GFR 0.5 +/- 2.1 ml
x min-1 x year-1; NS). The difference in the rate of decline of GFR was
significant (mean 2.7 ml x min-1 x year-1; P < 0.05). CONCLUSIONS:
Normotensive IDDM patients with nonprogressive microalbuminuria have a
stable GFR. Progression of UAE to diabetic nephropathy heralds a
progressive loss of kidney function. Efforts should be made to prevent the
progression from microalbuminuria to diabetic nephropathy in every IDDM
patient with microalbuminuria.