Higher Levels of Urinary Albumin Excretion Within the Normal Range Predict Easter Decline in Glomerular Filtration Rate in Diabetic Patients

OBJECTIVE - To assess the relationship between albuminuria, including elevation within the normal range, and decline in glomerular filtration rate < GFR) in diabetic patients. RESEARCH DESIGN AND METHODS - A total of 5,449 Japanese diabetic patients were categorized according to sex and urinary albumin-to-creatinine ratio (ACR; <5, 5-9, 10-29, 30-99, 100-299, 300-999, 1,000-2,999, and >= 3,000 mg/g) and followed for at least 5 years. The rate of change in estimated GFR (eGFR) adjusted for age and baseline eGFR was compared among ACR categories. RESULTS - A higher baseline ACR predicted a faster decline in eGFR for both sexes. Even within the normal range (<30 mg/g), ACR >= 10 mg/g in women and >= 5 mg/g in men was associated with a significantly greater rate of decline in eGFR relative to subjects with ACR <5 mg/g. CONCLUSIONS - Elevated ACR, even within the normal range, is associated with a faster decline in eGFR in diabetic patients.