RISK OF RADIOCONTRAST NEPHROPATHY IN PATIENTS WITH AND WITHOUT DIABETES-MELLITUS

The present study was designed to test whether altered renovascular re activity is associated with the increased risk of radio-contrast nephr opathy (RCN) in diabetics. We studied 50 patients (24 diabetics, 26 no ndiabetics) with chronic renal insufficiency undergoing cardiac cathet erization. Patients were randomized to receive either saline, or one o f three renal vasodilator/diuretic drugs-dopamine, atrial natriuretic peptide (ANP), or mannitol-by intravenous infusion during cardiac cath eterization. Renal blood flow (RBF) was measured by thermodilution at various time points during cardiac catheterization. RCN was defined as an increase in P(Cr) of at least 25% over baseline within 48 hours of cardiac catheterization. Baseline P(Cr) and creatinine clearance were similar in diabetics and nondiabetics (2.6 +/- 0.2 mg/dl vs. 2.4 +/- 0.1 mg/dl, and 32 +/- 3 ml/min vs. 34 +/- 3 ml/min, respectively), but baseline RBF was significantly lower in diabetics (154 +/- 21 ml/min/ kidney vs. 277 +/- 36 ml/min/kidney, P < 0.05). Diabetic patients expo sed to the three vasodilator/diuretic drugs had the greatest increase in RBF throughout cardiac catheterization. The incidence of RCN among the diabetics receiving those drugs was 83%, 83% and 75%, in the dopam ine, ANP and mannitol groups, respectively. In contrast, among the non diabetics in each of those groups the incidence of RCN was zero (all P < 0.05, diabetics vs. nondiabetics). In the saline control group the rates of RCN in the diabetics and nondiabetics were 43% and 38%, respe ctively (NS). In conclusion, the increased risk of RCN among diabetics was associated with exaggerated renovascular reactivity: baseline vas oconstriction and enhanced vasodilation with vasodilator/diuretic drug s. These same drugs, however, reduced the risk of RCN in nondiabetic p atients.