GAP (gestational diabetes and pharmacotherapy) – study protocol for a randomized controlled, two-arm, single-site trial

Background: Gestational diabetes (GDM) complicates 10% of pregnancies in the US. First-line treatment is medical nutrition therapy (MNT) and exercise. Second line is pharmacotherapy. The definition of what constitutes an unsuccessful trial of MNT and exercise has not been established. Tight glycemic control has been demonstrated to reduce GDM-related neonatal and maternal clinical complications. However, it could also increase rates of small-for-gestational age and carry negative effects on patient-reported outcomes such as anxiety and stress. We will study the effect of earlier and stricter pharmacotherapy in GDM on clinical and patient-reported outcomes. Methods: GDM and pharmacotherapy (GAP) study is a two-arm parallel, pragmatic randomized controlled trial, where 416 participants with GDM are randomized 1:1 to: 1) Intervention group - insulin initiation at 20% elevated glucose values on a weekly glucose log following MNT and exercise trial and insulin titration to keep elevated glucose values <20%; or 2) Active control group - insulin initiation at 40% elevated glucose values on a weekly log following MNT and exercise and insulin titration to keep elevated glucose values <40%. The primary outcome is a composite neonatal outcome of large-for-gestational-age, macrosomia, birth trauma, preterm birth, hypoglycemia, and hyperbilirubinemia. Secondary outcomes include preeclampsia, cesarean birth, small-for-gestational-age, maternal hypoglycemia, and patient-reported outcomes of anxiety, depression, perceived stress, and diabetes self-efficacy. Conclusions: The GAP study will investigate the optimal glycemic threshold for pharmacotherapy addition to MNT and exercise in GDM. The GAP study will promote standardization in GDM management and will have direct relevance for clinical practice.