OBJECTIVE: Whether the adipocyte-derived protein adiponectin is associated with insulin resistance independently of the effects of adiposity and the diabetic state is an important question. We explored, in a cross-sectional study of 486 Japanese nondiabetic women, the relationship between the calculated insulin resistance (homeostasis model assessment ratio (HOMA-R)) and adiponectin levels determined using a validated sandwich ELISA. DESIGN AND METHODS: All participants were stratified into tertiles for HOMA-R (approximately <1.5, 1.5< or = approximately <3.0, 3.0< or = approximately ) and the differences across tertiles of continuous variables were tested with ANOVA. Two-way ANOVA was used to determine possible relationships for plasma adiponectin between tertiles of HOMA-R and several stratified parameters. Multiple regression analyses were performed with HOMA-R or fasting serum insulin as dependent variable, and diastolic blood pressure (BP), body mass index (BMI), serum triglyceride (TG), leptin and adiponectin as independent determinants. RESULTS: Mean plasma adiponectin in the high HOMA-R group decreased compared with that in the low HOMA-R group both before (mean+/-s.e.m. 6.2+/-0.6 vs 9.2+/-0.3 microg/ml, P<0.001) and after adjustment for body fat mass (BFM) as kg or percent (0.31+/-0.04 vs 0.69+/-0.03, 0.18+/-0.02 vs 0.34+/-0.01, both P<0.001). HOMA-R was inversely associated with adiponectin levels both before (r=-0.37, P<0.001) and after adjustment for BFM (r=-0.49, -0.46, both P<0.001). After covariate adjustment for age, diastolic BP, BMI and serum TG, HOMA-R retained a significant correlation with adiponectin/BFM (kg). Both adiponectin and leptin were the significant determinants of HOMA-R or fasting insulin in multiple regression models. CONCLUSIONS: Adiponectin was inversely associated with insulin resistance in nondiabetic subjects, independently from age, BP, adiposity and serum lipids. Because adiponectin is thought to have an anti-atherogenic action, the presence of hypoadiponectinemia may predispose subjects to atherosclerosis, and may progress the atherogenesis in insulin resistance.
M Matsubara, S Katayose and S Maruoka
M Matsubara, S Maruoka and S Katayose
BACKGROUND: Adiponectin, a novel adipocyte-derived collagen-like protein, is the gene product of the adipose most-abundant gene transcript 1 (apM1), which has been considered to have anti-inflammatory and anti-atherogenic effects. OBJECTIVE: To characterize the relationship between adiponectin and leptin, the ob gene product, in normal-weight and obese women. DESIGN AND METHODS: In this cross-sectional study, we measured fasting plasma adiponectin by ELISA, leptin concentrations by RIA, and related parameters such as blood pressure, body mass index (BMI), body fat mass, lipids, fasting blood glucose and insulin in 353 non-diabetic adult women with a wide range of BMI values. RESULTS: Plasma adiponectin concentrations in women with the highest tertile of BMI (at least 25.0 kg/m(2)) were decreased compared with those in the middle (22.0-25.0 kg/m(2)) or lowest (<or=22.0 kg/m(2)) tertile of BMI (means+/-s.e.m.: 6.7+/-0.3 microg/ml compared with 8.6+/-0.4 microg/ml and 9.2+/-0.3 microg/ml; both P<0.0001). Serum leptin concentrations in women with the highest tertile of BMI were increased compared with those in women in the middle or lowest tertile of BMI (13.2+/-0.4 ng/ml compared with 8.1+/-0.2 ng/ml and 5.2+/-0.2 ng/ml; both P<0.0001). These relationships were similar after adjustment for BMI or body fat mass. Adiponectin was negatively correlated with serum leptin concentration, fasting immunoreactive insulin, calculated insulin resistance (homeostasis model assessment), BMI and body fat mass. These negative relationships became stronger after adjustment for BMI or body fat mass. In stepwise regression analyses, leptin was the significant independent variable for adiponectin, and adiponectin was also the significant independent variable for leptin before and after adjustment for BMI or body fat mass. CONCLUSIONS: In this study, we found an inverse correlation between adiponectin and leptin in vivo.
M Matsubara, K Namioka and S Katayose
OBJECTIVE: Inflammation has been suggested as a risk factor for the development of atherosclerosis, while some components of metabolic syndrome X have been related to inflammatory markers. We hypothesized that adipocyte secreting protein, adiponectin and leptin, for which have been demonstrated an association with metabolic syndrome X and coronary artery disease, may be associated with inflammatory markers in nondiabetic humans. DESIGN AND METHODS: We measured high-sensitivity C-reactive protein (hs-CRP), as an inflammatory marker, and adiponectin and leptin concentrations in 384 nondiabetic Japanese women (mean+/-s.e.m. age 53.6+/-0.8 Years, body mass index (BMI) 23.0+/-0.2 kg/m(2)) undergoing measurement of markers of metabolic syndrome X. RESULTS: The women who had a low-grade hs-CRP elevation (>2.0 mg/l) were significantly older and had higher BMI, body fat mass (BFM), total cholesterol (TC), triglyceride (TG), atherogenic index (AI=(TC-HDLC)/HDLC), where HDLC is high-density lipoproten-cholesterol), fasting blood glucose and leptin concentrations before and after adjustment for BMI or BFM, while lower HDLC and adiponectin concentrations before and after adjustment compared with women with normal CRP levels (<0.5 mg/l). BMI, BFM, TG, AI and leptin before and after adjustment were found to be correlated with hs-CRP levels, while HDLC and adiponectin before and after adjustment were inversely correlated (all P<0.0001). hs-CRP was independently associated with white blood cell count, blood urea nitrogen and AI and inversely with adiponectin/BFM in the stepwise regression analysis model. CONCLUSIONS: These data demonstrate a significant decrease in plasma adiponectin in low-grade chronic inflammation, and suggest that there is an important linkage between inflammation/adipose tIssue/atherosclerosis.