Increased renal arterial resistance predicts the course of renal function in type 2 diabetes with microalbuminuria

Type 2 diabetic patients often die because of end-stage
renal failure, but no definitive reliable factor predicting
long-term renal outcome has been identified. We tested
whether a renal arterial resistance index (R/I) >80, using
Doppler ultrasound technique, was predictive of worsening
renal function. The primary end points of the study were 1)
the course of glomerular filtration rate (GFR) and 2) the
albumin excretion rate in 157 microalbuminuric, hypertensive,
type 2 diabetic patients after a 7.8-year follow-up
period (range 7.1–9.2). Kaplan-Meier curves for the primary
end point (decrease of GFR >3.0 ml/min per 1.73 m2
per year) was two to three times more frequently observed
in patients with R/I >80. Four- to fivefold fewer patients
showed a regression to normoalbuminuria during the follow-
up period from baseline microalbuminuria in the cohort
with R/I >80. Overt proteinuria did develop in 24% of
patients with R/I >80 and in 5% of patients with R/I <80
(P < 0.01). In conclusion, intrarenal arterial resistance
appears to play a nontrivial role in deteriorating renal
function in type 2 diabetic patients. R/I is a noninvasive
diagnostic procedure, which strongly predicts the outcome
of renal function in type 2 diabetic patients, even when
GFR patterns are still normal. Diabetes 55:234–238, 2006