Prevention of gestational diabetes with a prepregnancy lifestyle intervention – findings from a randomized controlled trial

PURPOSE: Lifestyle intervention studies performed during pregnancy have shown inconsistent results in relation to prevention of gestational diabetes mellitus (GDM). Therefore, the aim of this study was to assess the effect of an intervention initiated already before pregnancy in prevention of GDM in high-risk women. PATIENTS AND METHODS: A randomized controlled trial was conducted in four Finnish maternity hospitals between the years 2008 and 2014. Altogether 228 high-risk women planning pregnancy were randomized to an intervention (n=116) or a control group (n=112). The risk factors were body mass index ≥30 kg/m(2) (n=46), prior GDM (n=120), or both (n=62), without manifest diabetes at study inclusion. Trained study nurses provided individualized lifestyle counseling every 3 months in addition to a group session with a dietician. The control group received standard antenatal care. GDM was defined as one or more pathological glucose values in a 75 g 2-hour oral glucose tolerance test, performed between 12 and 16 weeks of gestation and if normal repeated between 24 and 28 weeks of gestation. RESULTS: Within 12 months, 67% of the women (n=72) in the intervention group and 63% of the women (n=71) in the control group (p=0.84) became pregnant. The cumulative incidence of GDM among the women available for the final analyses was 60% (n=39/65) in the intervention group and 54% (n=34/63) in the control group (p=0.49). GDM was diagnosed already before 20 weeks of gestation in 60% (n=44/73) of the cases. CONCLUSION: The preconceptional lifestyle intervention applied in the present study did not reduce the incidence of GDM.