A novel smartphone app to change risk behaviors of women after gestational diabetes: A randomized controlled trial

AIMS: Women after gestational diabetes mellitus (GDM) are a risk group for cardiometabolic diseases but are hard to reach by conventional lifestyle programs. Therefore, we tested whether a novel, smartphone-delivered intervention, TRIANGLE, is accepted by women after GDM and alters cardiometabolic risk behaviors and outcomes. TRIANGLE targets gradual habit change of mind and emotion, physical activity, nutrition, and sleep. METHODS: We conducted a 6-month multicenter, randomized-controlled trial of TRIANGLE versus standard care with 66 women 3–18 months after GDM in Germany. The primary outcome was the proportion of women achieving ≥3 out of 5 Diabetes Prevention Program goals, i.e. physical activity ≥150 min/week (moderate to high intensity), fiber intake ≥15 g/1,000 kcal, fat intake <30% of total energy intake, saturated fat intake <10% of total energy intake, and weight reduction ≥5% if BMI ≥23 kg/m(2) or weight maintenance if BMI <23 kg/m(2). Intervention participants also rated the TRIANGLE app in the Mobile Application Rating Scale (uMARS). RESULTS: In the predefined, modified intention-to-treat analysis including 64 women, 6 out of 27 women in the intervention group [22%(10–40)] and 3 out of 27 women in the control group [11%(3–27)] reached the primary outcome (p = 0.47). In the predefined per-protocol intervention subgroup, the proportion was 4 out of 14 women [29%(11–55); p = 0.20 vs. control]. TRIANGLE app users were active on 42% of days and rated the app’s quality and perceived impact with 4.3±0.8 out of 5 uMARS points. CONCLUSIONS: This first trial did not show the efficacy of the TRIANGLE intervention. However, the app was well accepted and considered helpful by most users. Therefore, this trial supports further development and testing of TRIANGLE and other app interventions for women after GDM. Additionally, it identifies necessary adaptations in trial design to better accommodate non-intensive lifestyle interventions for this target group. TRIAL REGISTRATION: Trial registration at drks.de (DRKS00012996).