Significance of Umbilical Cord Leptin Profile during Pregnancy in Gestational Diabetes Mellitus—A Systematic Review and Meta-Analysis

Abstract

Background: The literature provides limited evidence of cord blood leptin levels in gestational diabetes mellitus (GDM), with contradictory and inconsistent results with respect to their possible implications for maternal, perinatal, and future complications. Methods: MEDLINE/PubMed, Embase, Scopus, and Web of Science databases were searched in order to investigate the state of evidence on the association of leptin profile in cord blood during perinatal complications in GDM. We critically assessed the risk of bias using the Newcastle-Ottawa scale. Meta-analyses were performed, and heterogeneity and publication bias were analyzed. Results: sixteen primary-level studies were included, recruiting 573 GDM and 1118 control pregnant women. Cord blood leptin levels were significantly higher in GDM participants compared to controls (standardized mean difference [SMD] = 0.59, 95% confidence intervals (CI) = 0.37 to 0.80, p < 0.001). All subgroups also maintained significant differences stratified by continents (Asia: SMD = 0.91, 95% CI = 0.45 to 1.37, p < 0.001; Europe: SMD = 0.38, 95% CI = 0.20 to 0.56, p < 0.001), analysis technique (ELISA: SMD = 0.70, 95% CI = 0.44 to 0.97, p < 0.001; RIA: SMD = 0.30, 95% CI = 0.11 to 0.49, p = 0.002), and sample source (plasma: SMD = 0.71, 95% CI = 0.33 to 1.09, p < 0.001; serum: SMD = 0.55, 95% CI = 0.34 to 0.77, p < 0.001). Conclusion: Cord blood leptin levels were significantly higher in GDM compared to controls. Further research is needed to clarify its role as a predictive biomarker of subsequent metabolic diseases in mothers with GDM and offspring.