Selective contribution of regional adiposity, skeletal muscle, and adipokines to glucose disposal in older adults

OBJECTIVES: To study the relationships between muscle mass, regional adiposity, and adipokines and glucose disposal in an older population. DESIGN: Cross-sectional analysis. SETTING: Community-dwelling volunteers from the Baltimore Longitudinal Study of Aging. PARTICIPANTS: Two hundred eighty men and 259 women with a mean age of 71.1 ± 0.4 (range 55-96) and complete data on fasting plasma adiponectin and leptin, oral glucose tolerance test (OGTT) (plasma glucose available at 0, 20, 40, 60, 80, 100, and 120 minutes), thigh computed tomography (CT), physical activity levels, and anthropometric measures. MEASUREMENTS: Participants were classified into eight groups according to the presence of global adiposity (body mass index > 27 kg/m ²), central adiposity (waist circumference > 88 cm for women and > 102 cm for men), and low muscle mass (CT thigh, lowest sex-specific tertile (93.8 cm ² in women and 110.7 cm ² in men) of adjusted thigh muscle area). Linear regression models were used to estimate the contribution of these eight groups to early glucose area under the curve (AUC) (t = 0-40 minutes), late glucose AUC (t = 60-120 minutes), and total glucose AUC (t = 0-120 minutes) from the OGTT. RESULTS: Regardless of muscle mass, individuals with a combination of central and global adiposity were more likely to have delayed glucose disposal rates (P < .05). A strong negative association was also found between circulating adiponectin levels and glucose disposal rates (early AUC, β = -0.14; late AUC, β = -0.20; and total AUC, β = -0.20; P < .05 for all three AUCs) after adjusting for regional adiposity, muscle mass, circulating leptin levels, physical activity, age, and sex. CONCLUSION: Older individuals with global and central adiposity may be at risk of glucose intolerance unrelated to low muscle mass.