Diabetes Care, Vol 20, Issue 3 265-271, Copyright © 1997 by American Diabetes Association
Predictors of renal morphological changes in the early stage of microalbuminuria in adolescents with IDDM
S Rudberg, R Osterby, G Dahlquist, G Nyberg and B Persson
Institute of Experimental Clinical Research, Arhus University, Denmark.
OBJECTIVE: To evaluate the impact of glycemic control, blood pressure,
lipid levels, glomerular filtration rate (GFR), age, and duration of IDDM
on the degree of structural glomerular changes in the transitional stage of
microalbuminuria. RESEARCH DESIGN AND METHODS: Fifteen adolescents (seven
boys and eight girls) with > 5 years of duration of IDDM and with
low-grade microalbuminuria (15-30 micrograms/min) participated. Seventeen
living kidney donors served as healthy control subjects. Five-year mean
HbA1c; 5-year mean systolic and diastolic blood pressure; GFR, cholesterol,
and triglycerides 2-5 years before renal biopsy; age; and duration of IDDM
were investigated and related to basement membrane thickness (BMT),
mesangial and matrix volume fractions, and the overall glomerulopathy index
[(BMT/10 + mat/glom, %) + matrix star volume]. RESULTS: BMT and the overall
diabetic glomerulopathy were increased in diabetic patients as compared
with control subjects (P < 0.001), whereas matrix volume fraction, but
not mesangial volume fraction, tended to be increased (P = 0.11). In
multivariate analysis, BMT was predicted by 5-year mean HbA1c, diabetes
duration, and previous GFR (R2 = 0.71, P = 0.003). With matrix volume
fraction as the dependent variable, BMT and diabetes duration were the only
significant determinants (R2 = 0.63, P = 0.003). Diabetes duration, 5-year
mean HbA1c, and GFR were the variables with an independent influence on the
overall diabetic glomerulopathy index (R2 = 0.72, P = 0.003). Preceding
blood pressure and lipid levels or age had no significant independent
influence on these morphometric measures. CONCLUSIONS: In the very early
stage of microalbuminuria in IDDM adolescents, a high percentage of the
variation in BMT and overall severity of glomerulopathy is explained by
prolonged hyperglycemia and diabetes duration. Previous glomerular
hyperfiltration may also add to the prediction of these morphological
changes.