Intrarenal resistive index in patients with type 2 diabetes mellitus with and without microalbuminuria

Diabetic nephropathy affects a subset of about 30% of patients with type 1 Diabetes Mellitus (DM); it also develops in a less defined percentage (20-30%) of patients with type 2, after a period of 15-20 years. It is usually divided into stages. The aim of this study is to assess the usefulness of duplex sonography with Doppler wave form analysis in the evaluation of early diabetic nephropathy, in order to detect patients at risk for irreversible renal disease. 262 patients (61 males, 201 females; age range: 48-81 years) with type 2 diabetes mellitus were studied; 100 healthy volunteers with no evidence of diabetes mellitus (74 females, 26 males; age range: 50-80 years) composed the control group. All of them underwent duplex Doppler sonography of the kidneys; a scanner with a 3.5 MHz transducer (Toshiba 270 SSA) was used, Pulsatily Index (P.I.) and Resistive Index (R.I.) of Doppler waveform were obtained at the intrarenal arteries; the average value of 3 bilateral measurements was taken. Doppler sonography was done by the same authors without knowledge of the patient group (case or control). Both indexes (PI. and R.I.) resulted to be higher in patients with DM compared to controls in patients with microalbuminuria: PI. = 1.49 +/- 0.34 vs. 1.07 +/- 0.06, p < 0.05; R.I. = 0.79 +/- 0.15 vs 0.60 +/- 0.03, p < 0.05. Even if our data have to be confirmed by further studies, they suggest that duplex Doppler sonography may be a useful complementary test in the evaluation of diabetic nephropathy, especially in the early stages, in order to identify more patients at risk of developing diabetic nephropathy.