The goal of this clinical trial is to use continuous glucose monitoring (CGM) to quickly detect and manage high blood sugar in pregnant women, early in pregnancy. The main questions it aims to answer are:

(1) any problems for the baby, such as being too large for their age, shoulder injuries (like broken bones), high bilirubin levels needing light treatment, low blood sugar, or needing to stay in the NICU; (2) any high blood pressure issues for the mother during pregnancy.

Data from continuous glucose monitoring (CGM) in the Glucose Lowering group tracked over time, will be compared to data from blinded sensors in the Usual Care group approximately every 4 weeks.

• Pregnant women who do not have diabetes and have a single, uncomplicated pregnancy will be enrolled by 14 weeks and 6 days. They will start by wearing a hidden CGM sensor to check for high blood sugar.

• The blinded CGM sensor data will be evaluated to determine if the following criterion is met: 5% to <25% of values >140 mg/dL

  • An initial assessment will be made after 5 days and for those not meeting the criterion, again after 10 days

• Participants meeting the CGM hyperglycemia criteria and the other study eligibility criteria will proceed to randomization, which must be performed by 16 weeks 6 days of gestation.

• Participants who do not meet the CGM hyperglycemia criteria will form an observational cohort, provided that HbA1c is <6.5% (48 mmol/mol)

Inclusion Criteria

1. Maternal age of 18 years and older

2. Singleton pregnancy

3. Gestational age up to 14w 6d of pregnancy, determined on ultrasound, for initiation of screening

   • Although it is preferable that ultrasound results be available prior to enrollment, if ultrasound results are not available at the time of enrollment, participant can have CGM initiated but will be dropped if not eligible after results are available

4. HbA1c <6.5% (48 mmol/mol) since onset of pregnancy

   • If HbA1c result not available at time of enrollment, participant can have blinded screening CGM initiated, but results will be needed prior to randomization to verify eligibility.

5. No prior history of gestational diabetes mellitus (GDM)

6. Able to read English or Spanish

Exclusion Criteria

1. Signs of abnormal fetal or placental development (suspected fetal anomaly or placenta accreta spectrum, low PAPPA) at first routine prenatal visit/ultrasound

2. Planned termination of pregnancy or any indications of miscarriage

3. Prior gastric bypass surgery

4. Pregravid diabetes (type 1 or type 2)

5. Unwillingness/inability to wear CGM sensor

6. Unwillingness to attend routine antenatal obstetric appointments

7. Use of corticosteroids by a route that can produce hyperglycemia (e.g., oral, intravenous, intramuscular, intra-articular) during the 7 days prior to initiating CGM screening or during the CGM screening

   • Topical and inhaled corticosteroids are acceptable

8. Use of insulin during the pregnancy prior to enrollment

9. Use of metformin within one week of the initiation of the blinded CGM sensor for screening or use of a GLP-1 or other weight-reduction medication that can affect glucose levels within 4 weeks of the initiation of the blinded CGM sensor for screening

10. Deemed unable to participate for medical reasons identified by their physician

Additional Criteria for RCT Eligibility

1. Screening CGM meeting study criteria for hyperglycemia: 5% to <25% time >140 mg/dL
2. Randomization by 16 week 6 days of pregnancy
3. No participation in a separate intervention trial.

Women of child bearing potential

Participants are initially masked from glucose results from continuous glucose monitoring.