Preventing gestational diabetes in pregnant women with obesity at high risk of gestational diabetes (UPBEAT-TIF)

INTERVENTION: Participants were randomised 1:1:1 to one of three groups: (1) lifestyle intervention consisting of dietary and physical activity advice delivered over 8 weeks; (2) lifestyle intervention plus metformin, initiated at 500 mg daily and titrated up to a maximum dose of 2000 mg/day; or (3) standard antenatal care. The lifestyle intervention focused on reducing glycaemic load, reducing saturated fat intake, increasing physical activity and reducing sedentary behaviour. CONDITION: Prevention of gestational diabetes mellitus (GDM) in pregnant women with obesity identified as being at high risk of developing GDM. ; Nutritional, Metabolic, Endocrine PRIMARY OUTCOME: Mean 24‐hour glucose concentration measured using continuous glucose monitoring (Dexcom G6 CGM) at baseline (13‐15+6 weeks’ gestation) and follow up (22‐25 weeks' gestation) SECONDARY OUTCOME: Dietary intake measured using a semi‐quantitative food frequency questionnaire, including glycaemic index, glycaemic load, saturated fat intake and other dietary variables, at baseline at 13–15+6 weeks’ gestation and follow‐up at 22–25 weeks’ gestation GDM diagnosis at 24 ‐ 28 weeks' gestation, according to IADPSG and NICE criteria, measured using the diagnosis of gestational diabetes mellitus using a 75 g oral glucose tolerance test at 24–28 weeks’ gestation Maternal outcomes, including gestational diabetes, hypertensive disorders, mode of delivery, pregnancy complications and hospital admission, and neonatal outcomes, including gestational age at birth, birthweight, birthweight centile, neonatal complications and neonatal unit admission, measured using data obtained from medical records at delivery and 4‐weeks postpartum Mean daytime glucose (07:00 ‐ 23:00 h, mmol/L), mean nocturnal glucose (23:00 ‐ 07:00 h, mmol/L), time in range: % time within 3.5 ‐ 6.7 mmol/L and 3.5 ‐ 7.8 mmol/L , time above range: % time above 6.7 mmol/L and above 7.8 mmol/L , time below range: % time below 3.5 mmol/L (TBR), glucose variability: standard deviation (SD) and coefficient of variation (CV) measured using continuous glucose monitoring (Dexcom G6 CGM) at baseline (13‐15+6 weeks’ gestation) and follow up (22‐25 weeks' gestation) Physical activity measured using a wrist‐worn accelerometer at baseline at 13–15+6 weeks’ gestation and follow‐up at 22–25 weeks’ gestation INCLUSION CRITERIA: 1. Women over 18 years of age 2. BMI = 30 kg/m² 3. Singleton pregnancy 4. Gestational age between 11 and 14+6 weeks’ gestation 5. Willing and able to give informed consent