Randomized Controlled Trial Intervention With New Nordic DIet in Women With GestatiOnal Diabetes Mellitus: iNDIGO

The study evaluates whether the New Nordic Diet, compared to routine care, will improve glucose control, among women developing gestational diabetes mellitus during pregnancy. Originally, a 10 wk intervention with qualified counseling on New Nordic Diet was planned, and effects on glycosylated haemoglobin A (HbA1c) at gestational age 37 weeks was planned as main outcome. Recruitment started in spring 2020 but had to be halted due to covid-19. Instead, we now conduct a more comprehensive version of the study, with a more intensive intervention consisting of distributed food bags plus dietary counselling for two weeks, and with continuous glucose monitoring during these two weeks to measure main outcome. This is more sensitive to small changes than is HbA1c. With this shorter and more intensive intervention we believe we can address our original hypothesis yet adjust to impacts of the covid-19 situation on the population and health care system.

Gestational diabetes mellitus (GDM) is associated with severe adverse outcomes for mother and newborn. Recently introduced Swedish guidelines on GDM diagnosis will at least double the prevalence of diagnosed women. The first line of treatment in GDM is diet and exercise treatment. Even so, there is a recognized knowledge gap as to what diet treatment is optimal. In routine care today, diagnosed women are provided by midwife with the same diet advice as patients with diabetes type 2 and these are broad and general. Only rarely are the diet advice provided by a dietician. In nutrition research, most evidence for health benefits of a diet has been demonstrated for the Mediterranean diet. Further, the New Nordic Diet (NND) was recently developed to mimic the Mediterranean diet yet builds on foods grown in the Nordic climate, thus focusing on gastronomical potential and sustainability. Interestingly, a diet intake in line with NND among Norwegian mothers was associated with lower risk for excessive pregnancy weight gain. In addition, associations have been shown between NND and lower risk for cardiovascular disease, obesity, inflammatory risk markers, serum lipids, colorectal cancer and total mortality. Hence, it seems likely that diet treatment with NND to women with GDM would be superior to routine care, but this has never been investigated. The main aim of the randomized controlled trial Intervention with new Nordic DIet in women with GestatiOnal diabetes mellitus (iNDIGO) is to test if the NND compared with usual care will improve glucose control in women with GDM. The iNDIGO study is a randomized parallel, single-blinded, controlled trial. In total, 50 women diagnosed with GDM are recruited and randomized to receive either a NND (intervention) or usual care (control) for 14 days. Participants receive a two-week menu and provided with food bags containing ingredients for dishes and foods to be used. Primary outcome is glycemic control (specifically time in target) measured using continuous glucose monitoring. Compliance to the dietary intervention will be tested using known dietary biomarkers and adherence questionnaires. Maternal socio-demographic and clinical data, biological samples, dietary intake and physical activity will be collected at enrollment and at the end of intervention (30-32 weeks' gestation).