The purpose of this study is to compare patient adherence to blood sugar monitoring during pregnancy using two different measurement methods in pregnancies complicated by pregestational type 2 diabetes (T2DM). Pregnant patients with T2DM are at risk of having larger babies, babies with low sugar levels in the first 24 hours of life, higher rates of cesarean delivery, stillbirth (death of baby inside the womb), and hypertensive or high blood pressure disorders of pregnancy, such as preeclampsia. Prior studies have shown that treating high blood sugars in pregnancy with medications can reduce these risks. To determine the amount of medication needed, recording of blood sugar levels is necessary. This trial aims to determine whether continuous blood sugar monitors have improved patient recording of blood sugar levels over finger stick blood sugar measurements.

Patients involved in the study will be assigned to either:

1. Fingerstick glucose monitoring (FSG)
2. Continuous glucose monitoring (CGM)

Patients will be randomize in a 1:1 ratio.

FSG Group: blood sugar is tested four times daily - once fasting and two hours after every meal (post-prandial). Blood will be tested using a glucometer, and values will be recorded in a blood sugar log from the time of enrollment to the time of delivery.

CGM Group: A CGM sensor will be placed on the patient's arm for blood sugar collection every 3-5 minutes. This data is sent to a phone application from the time of enrollment to the time of delivery. These sensors will need to be replaced every 14 days.

Percent adherence will be recorded from the time you were randomized to a study group until delivery.

About 1-2% of pregnant patients in the United States have pregestational type 2 diabetes (T2DM). The current standard of care for patients needing pharmacotherapy is to initiate basal and postprandial insulin as determined by the patient's reported blood glucose levels after a week of finger-stick glucose monitoring (FSG). This approach is dependent on the patient performing four finger sticks daily and keeping a record of those values. Titration of medication is also dependent on this process. Patient adherence with finger stick glucose testing is reported at about 50%. Continuous glucose monitors (CGMs) allow for continuous collection of blood glucose data without the patient needing to stick themselves or record their values. Increased adherence has been associated with improved maternal and neonatal outcomes. The goal of this randomized control trial is to determine if CGMs have greater adherence compared to FSG.

The investigator's first aim is to compare adherence to glucose monitoring using CGM versus finger stick monitoring in pregnant patients with T2DM. The investigator's second aim is to compare neonatal and maternal outcomes using CGM versus finger stick monitoring in pregnant patients with T2DM. The investigators hypothesize that CGMs will have increased adherence compared to finger stick glucose monitoring. The investigators also hypothesize that CGM will lead to improved glycemic control, improved neonatal outcomes, and improved maternal outcomes compared to finger stick glucose monitoring.

This is a prospective randomized controlled trial (RCT) comparing adherence to CGM versus FSG in patients with pregestational T2DM prior to initiating prenatal care. T2DM will be defined as the American Diabetes Association (ADA) criteria for diagnosis prior to the date of conception. Patients will receive a CGM after diagnosis will target blood glucose ranges between 65-140 mg/dL.

Participants will be screened, consented, and recruited at their initial prenatal visit. They will then be randomized to either the control FSG arm or the intervention CGM arm. Patients with T2DM are seen every 1 to 2 weeks for medication titration and BG checks, and the investigators would continue this workflow, following patients to delivery. If the patient requires insulin uptitration, a weight-based regimen as described by the ADA will be used. Patients will be seen every 1-2 weeks to titrate insulin to meet target ranges. The only difference in management between two groups will be the way the investigators measure blood glucose. Any indications for delivery will be managed in the same manner independent of group assignment based on the institution's clinical guidelines. After delivery, the investigators would review the documented neonatal and maternal outcomes and documented adherence.

The primary outcome is percent adherence, which will be calculated as number of days used with >75% of time coverage divided by the number of days from initiation to delivery for CGM and number of values reported divided by 28 (4 values are intended to be reported daily), divided by weeks from initiation to delivery for FSG. Secondary outcome is a composite of adverse neonatal outcomes, including the following measures: stillbirth, miscarriage, large for gestational age (LGA) of neonate defined as birth weight >90th percentile for gestational age, fetal hypoglycemia defined as glucose <40 mg/dL <48 hours after birth or glucose, hyperbilirubinemia, stillbirth or neonatal death, or birth trauma. Another secondary outcome is a composite of adverse maternal outcomes, including the following measures: maternal hypoglycemia < 60 mg/dL, shoulder dystocia, OASIS Injuries, operative delivery or c-section, postpartum hemorrhage, or hypertensive disorder of pregnancy.

Inclusion Criteria:

• singleton pregnancies
• fetuses without anomalies
• diagnosis of Type 2 diabetes
• initiation of prenatal care at <20 weeks gestation

Exclusion Criteria:

• diagnosis of Type 1 diabetes
• allergy to insulin
• inability to wear a continuous glucose monitor