Objective: Epicardial adipose tissue (EAT) is an interesting visceral fat pad with a particular location. EAT and subcutaneous adipose tissue (SAT) produce a wide range of adipokines. Some of them, including adiponectin and leptin, can influence the risk of development of diabetes and other associated metabolic and cardiovascular conditions. We sought to assess whether EAT and SAT adiponectin and leptin expression levels are different in diabetic patients with respect to nondiabetic subjects.
Subjects and methods: We collected samples of EAT from 120 patients and samples of SAT from 88 of the same group of patients undergoing elective cardiac surgery for coronary artery bypass grafting (n=69) or other procedures (n=51). After RNA isolation, adiponectin and leptin expression levels were analyzed by real-time reverse transcriptase PCR. Plasma levels were determined in small subsamples of subjects. Baseline clinical and treatment data were obtained from medical records.
Results: A total of 45 diabetic and 75 nondiabetic subjects were included in the study. Mean (s.d.) age was 70.1 (7.8) years and there were 32% women. EAT and SAT adiponectin and leptin mRNA expression levels were similar in the diabetic and the nondiabetic groups (EAT adiponectin 14.4 (4.3) vs 14.6 (3.4) arbitrary units (a.u.), P=0.79; SAT adiponectin 15.6 (4.7) vs 15.1 (3.9), P=0.54; EAT leptin 9.3 (interquartile range 2.5) vs 9.5 (1.9) a.u., P=0.72; SAT leptin 9.9 (3.6) vs 10.0 (2.5) a.u., P=0.96). These findings persisted after stratification for sex and coronary artery disease. Logistic regression models including possible confounders and a combination of diabetes and impaired fasting glucose as a dependent variable led to similar results. Plasma adiponectin levels were lower in diabetic patients, whereas leptin levels showed a nonsignificant trend.
Conclusion: Diabetic and nondiabetic subjects express similar EAT and SAT adiponectin and leptin levels. Counter-regulatory mechanisms of adiponectin and leptin expression in patients with established diabetes might partly account for these findings.