Gestational diabetes mellitus (GDM) is a common pregnancy complication, affecting approximately 14% of pregnancies globally, with prevalence increasing alongside obesity and type 2 diabetes. GDM increases women’s future risk of diabetes and cardiovascular disease and contributes to adverse metabolic outcomes in offspring, making pregnancy a critical opportunity for prevention and improved intergenerational health. Evidence suggests that pathways leading to GDM often begin before conception or early pregnancy, underscoring the importance of early preventive interventions (1). Women from culturally and linguistically diverse (CALD) communities experience a disproportionate burden of GDM and often face barriers to effective nutrition care, including language barriers, low nutrition literacy, culturally incongruent dietary advice and fragmented referral pathways. Although nutrition is central to GDM prevention and management, existing models of care frequently overlook the cultural and contextual factors shaping dietary behaviours, access and service engagement (2). The CoDe-GDM study aims to co-design a culturally adaptive nutrition care pathway that improves access to evidence-based nutrition support and strengthens engagement across GDM prevention, management and follow-up services among CALD women. CoDe-GDM is a consumer-led, three-phase mixed-methods study undertaken in partnership with CALD women, health services, community organisations and Diabetes Australia. Phase 1 will use implementation science and systems thinking to map current GDM prevention and care pathways and identify behavioural, cultural, organisational and health-system barriers and facilitators to accessing and utilising nutrition care. Phase 2 will use Experience-Based Co-Design and human-centred design approaches to co-design a culturally adaptive nutrition-centred pathway with consumers, family members, dietitians, midwives, diabetes educators and community stakeholders. Priority areas include culturally responsive nutrition education and dietary counselling, referral processes, service navigation, and engagement with existing nutrition and lifestyle programs. Phase 3 will pilot selected pathway components within routine antenatal and community-based services and evaluate feasibility, acceptability, cultural safety, reach, adoption, referral completion, continuity of care and implementation readiness. The study will generate a consumer-validated map of the GDM care continuum, identify priority opportunities to improve nutrition care, and produce a culturally adaptive model of care and implementation package for routine practice. By embedding culturally responsive nutrition support within antenatal care, CoDe-GDM shifts the focus from expecting CALD women to adapt to existing services towards designing nutrition care around their cultural preferences, lived experiences and service needs. The resulting model has the potential to strengthen engagement and continuity of nutrition care and provide a scalable approach to advancing equity in GDM prevention and management.