Diagnostic potential of elevated leptin in metabolic syndrome: A comprehensive review and meta-analysis

Metabolic syndrome (MetS) poses a substantial global health concern linked to rising rates of obesity and sedentary behaviors. Insulin resistance and dysregulated adipokines are central to its development, including elevated leptin levels. Produced mainly by adipocytes, leptin plays a pivotal role in regulating appetite, energy expenditure, and insulin sensitivity, thereby influencing the pathophysiology of MetS. However, earlier investigations have reported conflicting findings between circulating leptin levels concerning MetS. A systematic search of major research databases identified 14 eligible studies published before June 2023. Employing a random-effects model, the meta-analysis examined leptin concentrations in 1,106 patients with MetS and 1,171 control subjects. The analysis revealed significantly higher circulating leptin levels in MetS individuals with the condition compared to healthy controls with SMD: 0.84, 95% CI: 0.74 to 0.96, Z = 3.10, p < 0.001. Moreover, increased circulating leptin levels showed an association with a heightened risk of MetS, yielding an odds ratio was 1.14 (95% CI: 0.88 to 1.51). These findings suggest that leptin may serve as a valuable indicator for MetS, offering insights into early detection, the identification of new biomarkers and the opportunity for specialized pharmacological treatments.