Background
Gestational diabetes mellitus (GDM) is an abnormal glucose metabolism diagnosed during pregnancy that can have serious adverse consequences for mother and child. GDM is an exceptional health condition, as its management serves not only as treatment but also as prevention, reducing the risk of future diabetes in mother and child.

Objectives
This qualitative study aimed to explore how pregnant women experience and respond to GDM, focusing particularly on the role of the family environment in shaping women’s experiences.

Methods
The research was carried out in Vietnam’s Thái Bình province in April–May 2023. We conducted in-depth ethnographic interviews with 21 women with GDM, visiting them in their homes. Our theoretical starting point was phenomenological anthropology, and the data were analysed using a thematic analysis approach.

Results
At the centre of women’s experiences was the contrast between GDM as a biomedical and a social condition. Whereas GDM was biomedically diagnosed and managed in the healthcare system, it was often deemed insignificant or non-existent by family members. This made GDM a biomedically present but socially absent health condition. This paradox posed challenges to women’s GDM self-care, placing them in pioneering social positions.

Conclusions
The biomedical presence yet social absence of GDM turned women into pioneers at biomedical, digital, epidemiological, and family frontiers. This article calls for appreciation of pregnant women’s pioneering roles and for health systems action to involve women and families in the development of GDM policies and programmes at a time of sweeping global health changes.