Diabetes, Vol 45, Issue 12 1729-1733, Copyright © 1996 by American Diabetes Association
Glomerular hyperfiltration in the prediction of nephropathy in IDDM: a 10-year follow-up study
JW Yip, SL Jones, MJ Wiseman, C Hill and G Viberti
Unit for Metabolic Medicine, United Medical and Dental Schools, Guy's Hospital, London, U.K.
Glomerular hyperfiltration has been proposed as an independent risk factor
for the development of diabetic nephropathy in patients with IDDM. In a
case-controlled prospective study of IDDM patients without albuminuria,
serial glomerular filtration rate (GFR) measurements were performed over an
observation period of 10 years. A group of 25 IDDM patients (20 men, 5
women; initial age, 29 [17-49] years) with glomerular hyperfiltration (GFR
>135 ml x min(-1) x 1.73 m(-2)) were matched for age, sex, and duration
of diabetes with 25 IDDM patients (20 men, 5 women; initial age, 30 [17-48]
years) with glomerular normofiltration (GFR 83-135 ml x min(-1) x 1.73
m(-2)). GFR, urinary albumin excretion rate (AER), blood pressure, and
glycated hemoglobin were measured at baseline and at 5, 8, and 10 years.
The two groups had similar entry levels of blood pressure, AER, and
glycated hemoglobin. Metabolic control was similar in the two groups during
follow-up. The final GFR remained higher in the group with hyperfiltration
(122 [109-135] vs. 103 [95-111] ml x min(-1) x 1.73 m(-2); P = 0.02)
despite a nonsignificantly faster rate of fall of GFR compared with that of
the control group (2.54 [1.20-3.88] vs. 1.50 [1.01-1.99] ml x min(-1) x
year(-1); P = 0.14). A similar number of patients in each group progressed
to either microalbuminuria or macroalbuminuria (n = 4 vs. n = 3) or
developed hypertension (blood pressure, >160/95 mmHg; n = 3 vs. n = 4).
End-of-study AER was, however, higher in the group with hyperfiltration
(geometric mean [95% CI]: 18.9 [11.3-31.6] vs. 11.0 [8.1-15.0]; P = 0.05),
and baseline glomerular hyperfiltration was an independent determinant of
end-of-study blood pressure (P = 0.04). The strongest predictors of
end-of-study AER and blood pressure were their baseline values (P < 0.04
and P < 0.01, respectively). In conclusion, levels of AER and blood
pressure are the main risk factors for renal outcome, while glomerular
hyperfiltration appears to play a lesser role.