EARLY Pregnancy GLucose prOfiles in Women With and Without GDM Risk Factors: EARLY-GLOW

Background: Gestational diabetes mellitus (GDM) is associated with increased maternal and neonatal complications, including macrosomia, preeclampsia, and long-term metabolic consequences for both mother and child. Current screening methods, primarily the oral glucose tolerance test (OGTT), are typically performed between 24 and 28 weeks of gestation and may miss earlier metabolic alterations. Continuous glucose monitoring (CGM) offers a detailed assessment of glucose dynamics and could potentially identify subtle dysglycemia before GDM becomes clinically apparent. Objective: The EARLY-GLOW study aims to characterize glucose patterns during early pregnancy and identify CGM-derived thresholds for early dysglycemia in women with and without established risk factors for GDM. The study seeks to determine whether specific combinations of glucose level and duration of hyperglycemic exposure can distinguish women at increased risk of GDM before routine diagnosis. Additionally, it will explore the relationship between glucose profiles and modifiable lifestyle factors such as diet, physical activity, sleep, and stress, while evaluating the feasibility, usability, and acceptance of CGM technology during pregnancy. Study Design: EARLY-GLOW is a prospective, decentralized, observational pilot study conducted in Switzerland from July 2026 to June 2027. The study will recruit 48 pregnant women with singleton pregnancies at approximately 12 weeks of gestation. Participants will be stratified into two equal groups: women with at least one recognized GDM risk factor and women without risk factors. Methods: Participants will wear a blinded Dexcom G7 CGM continuously from approximately gestational week 12 until routine OGTT screening between weeks 24 and 28 (up to 16 weeks of monitoring). During the study, participants will periodically record fasting blood glucose measurements, dietary intake, meal photographs, sleep quality, physical activity, stress, and well-being through RE