Plasma adiponectin and insulin sensitivity in overweight and normal-weight middle-aged premenopausal women

Abstract Adiponectin has been reported to regulate systemic insulin sensitivity as a part of a broader control mechanism in energy balance. However, it is not clear whether adiponectin exerts its positive effects on insulin sensitivity equally in a wide range of obesity. We investigated the association of plasma adiponectin concentration with insulin resistance (IR) in a cross-sectional sample of 98 middle-aged premenopausal women with a wide range of obesity. In addition, we studied the relationship between adiponectin, body composition, and blood biochemical and cardiorespiratory fitness variables. Body composition and fat distribution were measured via dual-energy x-ray absorptiometry in normal-weight (NW) (n = 41, body mass index [BMI] 2 ) and overweight (OW) (n = 57, BMI ≥25 kg/m 2 ) women. Fasting blood samples were obtained; adiponectin, leptin, insulin, glucose, and insulin-like growth factor–I were measured; and IR index was calculated. The IR index from fasting plasma insulin and plasma glucose levels was estimated using the homeostasis model assessment (HOMA), as follows: fasting plasma insulin (in microliter units per milliliter) × fasting plasma glucose (in millimoles per liter)/22.5. Adiponectin was significantly higher ( P = .0001) in NW (14.7 ± 4.7 μ g/mL) compared with OW (9.9 ± 3.1 μ g/mL) women. Significant differences ( P β = −.259, P = .001) in the overall study group. Plasma adiponectin was only related to trunk fat–leg fat ratio ( β = −.242, P = .002) among NW subjects, whereas plasma adiponectin was related to fat-free mass ( β = .182, P = .0001) and HOMA ( β = −.576, P = .002) among OW women. The inverse relationship between adiponectin and leptin concentrations suggests that leptin may be involved in the regulation of adiponectin in middle-aged premenopausal women. Our data also demonstrate that adiponectin may play an important role in sustaining insulin sensitivity only in OW middle-aged premenopausal women.