Correlation of Continuous Glucose Monitoring and Glucose Tolerance Testing With Pregnancy Outcomes

Stanford University57 enrolled

Overview

Diabetic pregnant patients are at risk for adverse pregnancy outcomes, including larger than expected fetuses and unplanned operative deliveries, due to elevated blood glucose levels. the one-hour glucola test is currently used to screen pregnant patients for gestational diabetes. This involves ingesting a 50-gram glucose load, followed by a blood test one hour later. We wish to compare 7-day continuous glucose monitoring to the one-hour glucola test, and determine which one correlates better with adverse pregnancy outcomes as well as which one more accurately identifies patients at risk for adverse pregnancy outcomes.

All pregnant patients without pre-existing diabetes will be eligible for the study. Interest in participation will be determined at their initial prenatal visit. Those that are interested will be consented. Between 24-28 weeks of gestation, the recommended period of glucola testing, a soft sensor for continuous glucose monitoring system (CGMS) will be inserted superficially under the skin. The patient will be instructed on how to wear and care for the device. She will wear the CGMS for 7 days, then return to the clinic for removal of the device, and downloading of the data. She will perform the routine glucola test sometime between days 2 to 7 . Finger stick blood glucoses will be checked by the patient 2 times daily during the 7 days of wearing the CGMS. Results of CGMS will not be available to the patient or her physician until after completion of the pregnancy. The patient will be treated routinely, based on the results of the routine glucola test.

Study Type

INTERVENTIONAL

Allocation

Purpose

DIAGNOSTIC

Masking

NONE

Enrollment

Conditions

Interventions

The Seven Continuous Glucose Monitoring SystemDEVICE

Between 24-28 weeks of gestation, the recommended period of glucola testing, a soft sensor for continuous glucose monitoring system (CGMS) will be inserted superficially under the skin. The patient will be instructed on how to wear and care for the device. She will wear the CGMS for 7 days, then return to the clinic for removal of the device, and downloading of the data. Finger stick blood glucoses will be checked by the patient 2 times daily during the 7 days of wearing the CGMS.

Outcomes

Primary Outcomes

Correlation Between Glucose AUC and Birth Weight.

For each patient's CGM data, we calculated the total area under the curve (AUC) for values above the predefined cutoffs of 110, 120, 130, 140, and 180 mg/dL. Patients wore the CGM for different amounts of time; therefore, the total AUC for the entire duration of CGM use was divided by the number of 24-hour periods of data collection. We called these normalized values "AUC-110," "AUC-120," "AUC-130," "AUC-140," and "AUC-180," and they reflect both the magnitude and duration of hyperglycemic excursions above the predetermined thresholds in an average 24-hour period. Birth weight percentile was determined using birth weight data derived from 1999 and 2000 United States Natality datasets. The correlation coefficient (r) was calculated between birth weight percentiles and each of the following: AUC-110, AUC-120, AUC-130, AUC-140, AUC-180, and 1-hour GCT result.

Time frame: CGM measured 7 days at beginning of pregnancy,birth weight measured a time of delivery

Secondary Outcomes

Pregnancy and Delivery Characteristics for Participants With AUC-130 <= 22,000 and AUC-130 > 22,000

For our secondary outcome analyses,we chose to focus on AUC-130 because 130 mg/dL is a common threshold used when treating gestational diabetics. In addition, 130 mg/dL was the threshold used in an earlier pilot study performed at our institution because it had the best correlation with birth weight percentile. Secondary outcomes were compared between these two groups using the chi-square test. Data were analyzed using Stata 11.2. AUC-130 values were divided into "high" and "low" at a cutoff of 22,000, which was the 90th percentile of AUC-130 values.