Gestational diabetes mellitus induced variation in the macro-and micro-heterogeneity of N-glycoproteome in human milk from colostrum to mature milk.

Gestational diabetes mellitus (GDM) represents a systemic metabolic disorder manifesting during pregnancy, with its global prevalence rising annually. This study aimed to systematically investigate the differences in the glycoproteome of human milk from healthy (H) mothers and mothers with GDM, focusing on the dynamic changes from colostrum to mature milk by using LC-MS/MS. In total, for healthy mothers, 2474 glycopeptides and 249 glycosites were identified in colostrum and 1064 intact glycopeptides and 163 glycosites were identified in mature milk. For mothers with GDM, 1309 glycopeptides and 256 glycosites were identified in colostrum, and 353 glycopeptides and 97 glycosites were identified in mature milk. With respect to the type of glycans, mothers with GDM had higher proportions of sialylated N-glycans and lower high-mannose N-glycans than healthy mothers. Although glycan complexity of the two groups increased from colostrum to mature milk, the changes were more pronounced in the GDM group. The number of glycoproteins in the mature milk of healthy mothers (162) are significantly higher than those in the mature milk of mothers with GDM (96). During the extended lactation period, the proportions of fucosylated and high-mannose glycan chains significantly decreased, while the proportion of fucosylated-sialylated glycan chains significantly increased in the GDM group. These findings highlight the significant impact of GDM on milk glycoprotein composition and glycosylation patterns, suggesting potential nutritional implications for infants. These results provide a basis for studying the effects of different glycan compositions on infant health in mothers with GDM and healthy mothers.