Mokkala K, et al. - In this prospective study, researchers compared early pregnancy serum metabolic profiles of women developing gestational diabetes mellitus (GDM) with those remaining healthy in order to define the possible differences. They also assessed the ability of these metabolites to serve as predictive markers for GDM. Participants were overweight and obese [prepregnancy BMI (in kg/m²) ≥ 25 and > 30, respectively] pregnant women (prepregnancy median BMI: 28.5; IQR: 26.4–31.5; n = 357). Among women who later developed GDM vs those who continued to be healthy, 78 lipid metabolites varied in early pregnancy. Women developing GDM exhibited higher levels of several-sized VLDL particles and medium- and small-sized HDL particles, and lower levels of very large-sized HDL particles. Women who developed GDM also exhibited higher levels of amino acids including 2 branched-chain amino acids and GlycA. Overall, the early pregnancy metabolomic profile detected in women developing GDM was distinct especially because of the presence of small HDL particles.