Predicting Dysglycemia in Individuals With Gestational Diabetes Immediately Postpartum Using Continuous Glucose Monitoring

Study Overview
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Brief Summary
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Gestational diabetes is one of the most common medical disorders in pregnancy and is a major risk factor for the postpartum development of dysglycemia. Despite the high risk of developing dysglycemia, 50-80% of women with gestational diabetes are not receiving testing within a year postpartum. The investigators will conduct a prospective cohort study to examine the use of continuous glucose monitoring immediately postpartum to estimate the risk of maternal dysglycemia postpartum.

Detailed Description
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Gestational diabetes is one of the most common medical disorders in pregnancy and affects up to 18% of pregnancies. It is associated with an increased risk of both maternal and neonatal complications. Importantly, gestational diabetes is a major risk factor for the postpartum development of pre-diabetes or type 2 diabetes (together referred to as dysglycemia). Specifically, half of people with gestational diabetes will develop dysglycemia within 10 years of delivery. Despite the high risk of developing dysglycemia, 50-80% of women with recent gestational diabetes are not receiving testing within a year postpartum. There are likely many factors contributing to this low screening rate. These include individual factors such as socioeconomic status and maternal age, as well as the nature of the guideline recommended test itself. The Diabetes Canada 2018 Clinical Practice Guidelines recommend screening for maternal dysglycemia between 6 weeks to 6 months postpartum with a 75g oral glucose tolerance test (OGTT). This recommendation is based on expert opinion. While the 75g OGTT is thought to be the gold-standard for screening for dysglycemia postpartum, it has many pitfalls. First, the OGTT is widely disliked by women as it is time consuming and inconvenient. It requires consuming a sugary drink in addition to two separate venipunctures. Second, the 75g OGTT is notoriously unreproducible. Finally, it takes only a snap shot of a woman's glucose and insulin response with only two measurements over two-hours. Emerging technologies are changing the landscape of diabetes care. Continuous glucose monitoring (Freestyle Libre 2) is one such technology. People easily insert a small cannula just under the skin using an applicator. While the device is in place, it measures interstitial glucose concentrations every 15 minutes. It is a small disc ( size of a quarter) and it can be worn during typical daily activities such as sleeping, showering, and exercising. The sensor can store up to 8 hours of glucose readings in 15-minute intervals. People scan the sensor using a smartphone or reader to upload glucose readings to the Freestyle Libre 2 app, which can be viewed by a clinician and/or researcher. Continuous glucose monitoring gives a detailed picture of glycemic excursions throughout the day including both fasting and postprandial states. There are currently no published studies examining the use of continuous glucose monitoring postpartum. Furthermore, no studies have examined continuous glucose monitoring's potential role in diagnosis of maternal dysglycemia postpartum. There is an unmet need to improve postpartum screening for individuals with gestational diabetes so that high risk individuals do not miss the opportunity for early treatment. To address this, the investigators will perform a study examining the use of continuous glucose monitoring immediately postpartum to estimate the risk of maternal dysglycemia postpartum. This is an observational study which aims to see if CGM can be used to diagnose diabetes. The CGM device in this study will be used for diagnosis and not as an intervention.

Official Title
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Predicting Dysglycemia in Individuals With Gestational Diabetes Immediately Postpartum Using Continuous Glucose Monitoring

Conditions
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Gestational Diabetes, Prediabetes; Complicating Pregnancy, Type 2 Diabetes, Pregnancy Related, Glucose Metabolism Disorders, Metabolic Disease, Endocrine System Diseases

Intervention / Treatment
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* Device: Freestyle Libre 2
* Device: Freestyle Libre 2


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant individuals age 18 and older Diagnosed with gestational diabetes by the Diabetes Canada guidelines (including both the preferred or alternate testing approaches) or have an HbA1c of 6.0-6.4% during pregnancy Have any of the following: have an elevated fasting glucose (≥ 5.3 mmol/L) on the diagnostic 75g OGTT in pregnancy; required insulin or metformin for treatment during pregnancy; body mass index (BMI) ≥ 25kg/m2, yes/no (<27 weeks gestation BMI of ≥25 kg/m2 or ≥27 weeks gestation predicted BMI of ≥ 25 kg/m2 using (current weight in kg - 10kg)/height in meters2) Planned in-hospital delivery Able to provide informed consent Willingness to use the study device and complete assessments Have access to email in order to complete participant questionnaire through REDCap Exclusion Criteria: Non-gestational diabetes (i.e. pre-existing diabetes) Planned x-ray, MRI or CT within 3 weeks postpartum Has an implantable medical device (ex. pacemaker) On medications known to affect glucose metabolism (for example glucocorticoids, metformin etc.) On medications which may interfere with the Freestyle Libre 2 accuracy (for example Vitamin C >1000mg/day) Unable to speak and understand French or English Unable to consent or declined informed consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Pregnant women diagnosed with gestational diabetes<br>Pregnant individuals who have been diagnosed with gestational diabetes during the current pregnancy | Device: Freestyle Libre 2<br>* Participants will wear a continuous glucose monitoring device, the Freestyle Libre 2, for two weeks following delivery.<br>Device: Freestyle Libre 2<br>* Participants will wear a second continuous glucose monitoring device, the Freestyle Libre 2, for two weeks at 4-6 months postpartum and before their standard of care postpartum bloodwork after having gestational diabetes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| New diagnosis of maternal diabetes or prediabetes based on 75g OGTT | Maternal diabetes defined as fasting plasma glucose ≥ 7.0mmol/L or 2-hour plasma glucose of ≥ 11.1 mmol/L and maternal prediabetes defined as fasting plasma glucose 6.1-6.9 mmol/L or 2-hour plasma glucose of 7.8-11.0 mmol/L. Both are defined by the Diabetes Canada 2018 Clinical Practice Guidelines. | 4-6 months postpartum | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| New diagnosis of maternal diabetes or prediabetes based on postpartum HbA1c | Diabetes is defined as HbA1c ≥ 6.5% and prediabetes is defined as HbA1c 6.0-6.4%. | 4-6 months postpartum | 
| Acceptability of testing using the device based on an acceptability questionnaire | The Acceptability Questionnaire for the Freestyle Libre 2 Postpartum will be completed at two points throughout the study. Scores can range between 7 and 60, with a higher score indicating a worse outcome. | 15-17 days postpartum; 4-6 months postpartum | 
| Glycemic variability reflected by coefficients of variation and standard deviations of blood glucose data | Blood glucose data will be collected using the Freestyle Libre 2 continuous glucose monitoring system. | Delivery to 2 weeks postpartum | 
| New diagnosis of dysglycemia and additional health outcomes | Information on new pre-diabetes, type 2 diabetes, and overt diabetes diagnoses and additional health outcomes will be obtained through administrative provincial databases and chart review. | 1, 2 and 5 years postpartum | 
| Cost component analysis of CGM vs. 75g OGTT | Costs of assessing blood glucose via CGM versus lab-derived OGTT results will be compared. | 4-6 months to 5 years postpartum | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Pregnancy, Gestational Diabetes, Prediabetes, Prospective Cohort Study, Type 2 Diabetes, CGM, Continuous Glucose Monitoring, Flash Glucose Monitoring, Screening