Fructosamine, glycolysis intermediate pyruvate, BCAAs (valine, leucine and isoleucine) and ACAAs (tyrosine) along with acetoacetate and gGT concentrations were all positively correlated with GDM, while insulin indices assessed by HOMA scores, revealed a negative association between β-cell function with GDM diagnosis, but no difference in insulin resistance indices. This evidence concerns the gene INS and gestational diabetes.