Influence of age and visceral fat area on plasma adiponectin concentrations in women with normal glucose tolerance

Background: Age-related adiponectin concentration has been discrepantly reported. We investigated the distribution of adiponectin by age in healthy women with normal glucose tolerance (NGT) and the relationship of adiponectin with visceral fat area (VFA). Methods: Three-hundred fifty-nine women (age: 38 ± 0.6 years, BMI: 26.5 ± 0.2 kg/m²) were categorized into 4 age-groups: 20-29, 30-39, 40-49, and 50-64 years. Computed tomography was performed to measure abdominal fat area and adiponectin, TNF-α, interleukin-6 (IL-6), CRP, insulin, free fatty acid (FFA), and blood urea nitrogen (BUN) were determined. Results: No significant differences were observed in BMI, total body fat percent and concentrations of insulin, IL-6 and CRP among age-groups. Waist circumference, total fat area at L4, and FFA were significantly higher only in postmenopausal women than in previous decades of premenopausal women. VFA, adiponectin and TNF-α concentrations are significantly higher in older women than in younger women. Higher adiponectin concentration in older women was clearly shown even after adjustment for VFA (P < 0.05). Age per se was positively correlated with plasma adiponectin concentrations (r = 0.21, P < 0.001) and these relationship became stronger (r = 0.36, P < 0.001) after controlled for VFA. VFA was negatively correlated with adiponectin (r = - 0.16, P < 0.01) in total studied population. However, when analyzed subgroups separately, a strong negative correlation (r = - 0.37, P < 0.001) was found in younger women (< 40 years), while a weak significant relationship (r = - 0.18, P < 0.05) was found in older women (≥ 40 years). In a multiple stepwise regression model to predict adiponectin, only age and VFA remained in the model at P < 0.001. Conclusions: We observed a significant positive relationship between plasma adiponectin and age, even after adjustment for visceral adiposity. These associations suggest that adiponectin concentrations are affected by visceral adiposity, with additional independent effects of age.