The associations between plasma adiponectin, ghrelin levels and cardiovascular risk factors

Objective: Ghrelin is a recently discovered peptide, which is produced primarily in the stomach. This orexigenic peptide participates not only in the induction of mealtime hunger but also in long-term body weight regulation and energy homeostasis. Adiponectin is a protein secreted by adipocytes, and has been proposed to mediate obesity-related insulin resistance. Moreover, concentrations of adiponectin are reduced in individuals with obesity, insulin resistance and cardiovascular disease. However, human data are sparse about the direct relationship between adiponectin, ghrelin and cardiovascular risk factors including insulin resistance. Design: Three hundred and thirty-eight elderly Korean women (mean age ± S.D., 72.3 ± 5.5 years) were included in the present study. Methods: Plasma ghrelin and adiponectin levels were measured by RIA. Anthropometric measurements were taken and a 75 g oral glucose tolerance test performed. Fasting insulin and lipid profile were measured and insulin resistance was determined using the homeostasis model assessment insulin resistance index (HOMA-R) and the quantitative insulin sensitivity check index. Results: Plasma adiponectin levels were negatively correlated with central obesity indices such as waist circumference (r = -0.27, P < 0.001) and waist-to-hip ratio (WHR) (r = 0.32, P < 0.001), and with insulin resistance indices such as fasting insulin (r = -0.17, P 0.004) and HOMA-R (r = -0.13, P = 0.035). Plasma ghrelin levels were negatively correlated with WHR (r = -0.12, P = 0.03), but plasma adiponectin and ghrelin levels were not correlated (r = 0.03. P = 0.66). Multiple regression analysis showed that adiponectin was associated with WHR, fasting insulin and fasting glucose levels. When ghrelin was used as a dependent variable, only WHR remained in the final fitted model. Conclusion: Fasting plasma adiponectin and ghrelin levels were found to be associated with central obesity or insulin resistance. However, plasma adiponectin and ghrelin concentrations were not associated with each other in elderly Korean women.