Based on this background, the present systematic review with meta-analysis had the objective of exploring whether there are differences in cord blood leptin levels between pregnant women with GDM and controls in order to define the state of evidence about the cord leptin profile during pregnancy in GDM, its role in the pathophysiology, and its potential use as a predictive marker for the subsequent occurrence of diabetes and other metabolic disorders in GDM mothers and infants. Here, LEP is linked to diabetes mellitus.