Abnormal Albuminuria as a Predictor of Mortality and Renal Impairment in Chinese Patients With NIDDM

Abstract

OBJECTIVE Microalbuminuria predicts mortality in non-insulin-dependent diabetes mellitus (NIDDM), but its association with deterioration of renal function remains more controversial than in insulin-dependent diabetes mellitus (IDDM). Using albumin-to-creatinine ratios (ACRs) in random spot urine samples is a convenient method for evaluating albuminuria. We studied prospectively the predictive values of albuminuria in NIDDM when assessed by this urine measurement. RESEARCH DESIGN AND METHODS Between 1991 and 1992, we restudied the clinical and biochemical status of 403 Chinese NIDDM patients recruited in 1989 after a follow-up period of 26.6 ± 3.2 months (mean ± SD). Spot urine ACR was measured on two occasions and microalbuminuria was defined as a mean ACR between 5.6 and 38 mg/mmol. RESULTS From the original cohort, 29 patients had died mostly because of cardiovascular events with or without renal failure. The overall relative risk of death in patients with abnormal albuminuria was 7.1 (P < 0.001) (microalbuminuria: 3.7, P = 0.04; macroalbuminuria: 11, P < 0.001). On multivariate analysis, the independent predictive factors for mortality were plasma creatinine (wald = 12.1, P < 0.001) and glucose concentrations (wald = 10.4, P < 0.001) in the normo- and microalbuminuric patients (n = 11) and age (wald = 4.4, P = 0.03) and plasma creatinine (wald = 8.2, P < 0.01) in the macroalbuminuric group (n = 18). In the survivors (n = 374), baseline spot urine ACR was independently associated with 2-year spot urine ACR in the normo- (P < 0.001), micro- (P < 0.01), and macroalbuminuric groups (P = 0.01). In addition, baseline spot urine ACR was independently related to 2-year plasma creatinine (P = 0.01) in the macroalbuminuric group. The rates of change of the reciprocal of plasma creatinine (Δ [Cr]−1) were −27.3 ± 62.5, −43.4 ± 68.6, and −108.8 ± 98.81·μmol−1·months−1 in the normo-, micro-, and macroalbuminuric groups, respectively (P < 0.001). The Δ [Cr]−1 was independently and inversely related to the baseline spot urine ACR (P < 0.001) and 2-year systolic blood pressure (P < 0.001). CONCLUSIONS Abnormal albuminuria as indicated by a random spot urine ACR > 5.6 mg/mmol predicts increased mortality and is associated with the progression of albuminuria and deterioration of renal function in Chinese NIDDM patients.