Effect of the New Nordic Diet compared with usual care on glucose control in gestational diabetes mellitus : Study protocol for the randomized controlled trial intervention with new Nordic DIet in women with GestatiOnal diabetes mellitus (iNDIGO)

Background: Gestational diabetes mellitus (GDM) is a pregnancy complication associated with short- and long-term health consequences for mother and child. First line treatment is diet and exercise but there is a recognized knowledge gap as to what diet treatment is optimal. A healthy Nordic diet has been associated with improved health but no studies in women with GDM exist. The New Nordic Diet (NND) is an initiative with the purpose to develop a healthy Nordic diet including foods with the potential to grow in Nordic countries; including fruit, berries, vegetables, whole-grain cereal products, nuts, fish, and rapeseed oil. The purpose of the intervention with new Nordic DIet in women with GestatiOnal diabetes mellitus (iNDIGO) is to test if the NND compared with usual care improves glucose control in women with GDM. Methods: The iNDIGO study is a randomized parallel controlled trial where 50 women with GDM will be randomized to either an NND or usual care for 14 days (30–32 weeks of gestation). Participants in the NND group will receive menus and food bags containing foods to be consumed. Primary outcome is glycemic control (time in target) measured using continuous glucose monitoring. Compliance to the dietary intervention will be tested using dietary biomarkers and adherence questionnaires. Conclusion: Diet treatment represents first line treatment in GDM but it remains unclear what type of diets are effective. iNDIGO is an efficacy study and will provide evidence as to whether a healthy Nordic diet can improve glucose control in women with GDM.