Are the associations of plasma leptin and adiponectin with type 2 diabetes independent of obesity in older Chinese adults?

Abstract

China has experienced a rapid increase in diabetes. In this study, we assessed whether the associations of two adipocyte-derived hormones, leptin and adiponectin, with type 2 diabetes are independent of obesity in older Chinese adults. In this matched case-control study, each of the 619 diabetes and impaired fasting glucose (IFG) cases aged 60-96 years was matched to a control by age, sex, waist circumference and body mass index (BMI). Before matching, IFG and diabetes cases had significantly lower adiponectin and higher leptin concentrations than the participants with normal glucose. After matching for age, sex, waist circumference and BMI, the differences between cases and controls remained significant (p < 0.001) in adiponectin but not in leptin (p = 0.77). Adjusted odds ratios for the combined outcome of diabetes and IFG were 1.03 (95% confidence interval: 0.88, 1.21; p = 0.71) for one standard deviation increase in plasma leptin and 0.79 (95% confidence interval: 0.69, 0.91; p < 0.001) for one standard deviation increase in plasma adiponectin. Without adjustment for obesity related body size measurements of waist circumference and BMI, both adiponectin and leptin are associated with diabetes and IFG. After adjustment, adiponectin is independently associated with diabetes and IFG, but there is no independent association between leptin and either diabetes or IFG. Our findings suggest that adiponectin provides extra-predictive power beyond obesity while leptin does not independently predict the risk of diabetes and IFG in older Chinese adults.