Higher Levels of Urinary Albumin Excretion Within the Normal Range Predict Faster 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.