Strict Versus Permissive Thresholds for Initiation of Pharmacotherapy in Gestational Diabetes (START 2)

Pregnancy is a state of insulin resistance to ensure that the growing fetus has ample nutrition. Gestational Diabetes (GDM) develops in pregnant patients with pancreatic dysfunction that leads to impairment of glucose tolerance.

Various studies have examined the benefit of treatment for GDM, including the 2005 Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS) and the 2009 Landon et al randomized controlled trials. These studies found that treatment was associated with a significant reduction in newborn complications of perinatal death, shoulder dystocia, large for gestational age infants, cesarean delivery, and birth trauma. The specific threshold value for initiation and up-titration of medical therapy is unknown. Lack of evidence leads to a wide variation in clinical practice of pharmacological initiation and titration for GDM. A systematic review and meta-analysis by Caissutti in 2019 analyzed criteria for initiating pharmacotherapy for GDM and noted the following: 12 of 15 trials initiated pharmacotherapy after 1-2 abnormal values over 1-2 weeks, 2 studies initiated pharmacotherapy after 50% of overall values were abnormal, and 1 study initiated pharmacotherapy after 30% of overall values were abnormal. However, there have been no randomized controlled trials of head-to-head comparison of different thresholds.

The aim of our study is to compare neonatal and maternal outcomes using different thresholds for the initiation and titration of pharmacotherapy for GDM using continuous glucose monitor. Our goal is to compare a Strict and permissive threshold. The Strict study arm target range will be 65-120 mg/dL, with time in range goal of 70%. The permissive study arm target range will be 65-140 mg/dL, with target time in range goal of 70%.

Inclusion criteria

• Live, non-anomalous fetus
• Literacy in English, Spanish, Mandarin, or Arabic
• Patients are also required to provide consent, demonstrate an understanding of the purpose of the study, and agree to the study protocol.

Exclusion criteria

• <18 years at EDD
• pre-existing diabetes or diagnosis of GDM prior to 24 weeks
• multi-fetal gestation
• known major fetal anomaly
• known allergy to insulin
• chronic maternal corticosteroid use
• diagnosis of GDM based on finger sticks alone
• patients who have contraindication to oral glucose tolerance test
• a primary language other than English, Spanish, Mandarin, or Arabic