We investigated circulating HMOs in the postpartum period, and assessed their short-term modulation by glucose and insulin, and the relationship between plasma and milk HMO profiles.<h4>Methods</h4>At 5-7 weeks postpartum, 28 women (16 with prior gestational diabetes [GDM]; 18 who were breastfeeding) underwent both a 75 g oral glucose tolerance test (OGTT) and a hyperinsulinaemic-euglycaemic clamp. Here, INS is linked to gestational diabetes.