Serum adiponectin concentration in relation to body fat distribution and tissue insulin sensitivity in the glucose clamp study

Abstract

To study serum adiponectin level in relation to body fat distribution and tissue insulin sensitivity by using the extended hyperinsulinemic euglycemic clamp technique. Extended hyperinsulinemic euglycemic clamp was performed in 44 Chinese individuals with normal glucose tolerance from Shanghai area, including 12 subjects with normal weight [body mass index (BMI) < 25 kg/m(2)], 19 with overweight (25 kg/m(2) < or = BMI < 30 kg/m(2)), and 13 with obesity (BMI > or = 30 kg/m(2)). The rate of insulin-mediated glucose disposal (Rd) during the steady state of glucose clamp was used to assess the peripheral tissue insulin sensitivity. Total body fat depots [BMI, percentage of body fat (FAT%), and body fat mass (FM)], regional body fat depots [waist circumference (W), hip circumference (H), W and H ratio (WHR), abdominal subcutaneous fat area (SA), intra-abdominal fat area (VA), and femoral subcutaneous fat area (FA)] were measured on all subjects. Fasting serum adiponectin level was determined by radioimmunoassay. (1) After the adjustment for age and sex, the serum adiponectin concentrations in the overweight and obesity groups were (8.7 +/- 4.8) mg/L and (6.7 +/- 0.8) mg/L, both significantly lower than that in the normal weight group [(15.7 +/- 1.8) mg/L, both P < 0.01]. (2) Serum adiponectin concentration was negatively correlated with BMI, W, WHR, FAT%, FM and VA, especially with W and VA (r = -0.46, P < 0.01, and r = -0.53, P < 0.01). (3) Serum adiponectin concentration was positively correlated with Rd (r = 0.52, P < 0.01) and the rate of glycogen synthesis (r = 0.36, P < 0.05), and was negatively correlated with free fatty acid level (r = -0.41, P < 0.05). (4) Stepwise regression analysis indicated that in addition to sex, BMI, WHR or VA and SA, serum adiponectin level was also the independent contributing factor for Rd, which explains 3.52% and 4.84% of the variance respectively (P all < 0.05). (1) The decrease in serum adiponectin level is associated with the increase of total body fat depot, especially the increase of total body fat depot in intra-abdominal fat area. (2) Serum adiponectin level is an independent contributing factor for insulin sensitivity.