Biomarkers of renal function and cognitive impairment in patients with diabetes

OBJECTIVE - Kidney disease is associated with cognitive impairment in studies of nondiabetic adults. We examined the cross-sectional relation between three measures of renal function and performance on four measures of cognitive function in the Action to Control Cardiovascular Risk in Diabetes Memory in Diabetes (ACCORD-MIND) study. RESEARCH DESIGN AND METHODS - The relationships among estimated glomerular filtration rate (eGFR),60 mL/min/1.73m ² (n = 2,968), albumin/creatinine ratio (ACR)≥30 μg/mg (n = 2,957), and cystatin C level .1.0 mg/L (n = 532) with tertile of performance on the Mini-Mental State Examination, Rey Auditory Verbal Learning Test (RAVLT), Digit Symbol Substitution Test (DSST), and Stroop Test of executive function were measured. RESULTS - In adjusted logistic regression models, ACR ≥30 μg/mg was associated with performance in the lowest tertile, compared with the highest two tertiles, on the RAVLT (odds ratio 1.30, 95%CI 1.09-1.56, P = 0.006), equivalent to 3.6 years of aging, and on the DSST (1.47, 1.20-1.80, P = 0.001), equivalent to 3.7 years of aging. Cystatin C > 1.0 mg/L was borderline associated with the lowest tertile on the DSST (1.81, 0.93-3.55, P = 0.08) and Stroop (1.78, 0.97-3.23, P = 0.06) in adjusted models. eGFR was not associated with any measure of cognitive performance. CONCLUSIONS - In diabetic people with HbA _1c >7.5% at high risk for cardiovascular disease, decreased cognitive function was associated with kidney disease as measured by ACR, a measure of microvascular endothelial pathology, and cystatin C, a marker of eGFR.