Cross-sectional associations of albuminuria and C-reactive protein with functional disability in older adults with diabetes

Abstract

OBJECTIVE - To examine the relationship between albuminuria, inflammation, and disability in older adults with diabetes. RESEARCH DESIGN AND METHODS - Data were from 1,729 adults (≥60 years) with diabetes in the National Health and Nutrition Examination Survey, 1999-2008. Disability in activities of daily living (ADL), instrumental activities of daily living (IADL), leisure and social activities (LSA), general physical activities (GPA), and lower-extremity mobility (LEM) was obtained from self-reports. Urinary albumin-to-creatinine ratio (UACR) (mg/g) was categorized into normal (UACR <30 mg/g), microalbuminuria (UACR 30-300 mg/g), and macroalbuminuria (UACR >300 mg/g). C-reactive protein (CRP) levels were quantified by latex-enhanced nephelometry. RESULTS - In the full-adjusted model, microalbuminuria was associated with disability in ADL, LSA, and LEM with corresponding odds ratios (ORs) (95% CIs) of 1.51 (1.16-1.98), 1.62 (1.23-2.14), and 1.34 (1.03-1.74), respectively, compared with participants without albuminuria. Macroalbuminuria was associated with disability in ADL, IADL, and LEM with corresponding ORs (95% CIs) of 1.94 (1.24-3.03), 1.93 (1.23-3.02), and 2.20 (1.38-3.49), respectively, compared with participants without albuminuria. Elevated CRP (>0.3 mg/dL) was associated with increased odds of disability in ADL and LEM, with corresponding ORs (95% CIs) of 1.28 (1.00-1.62) and 1.68 (1.34-2.11), respectively. Subjects with both albuminuria and elevated CRP had higher odds of disability than individuals with no albuminuria and normal CRP. CONCLUSIONS - Albuminuria and inflammation were independent correlates for disability among older adults with diabetes. There was an interaction of albuminuria and elevated CRP on disability, suggesting that the presence of subclinical inflammation may amplify the effect of albuminuria on disability in older adults living with diabetes. © 2011 by the American Diabetes Association.