CGM Accuracy in Pregnancy Study

December 4, 2025 updated by: Hospital Mutua de Terrassa

Evaluation of the Accuracy of Continuous Glucose Monitoring Systems and Educational Needs in Pregnant Women With Diabetes: A Comparison Between Dexcom One Plus and FreeStyle Libre 2 Plus

Pregnancy in women with diabetes remains a high-risk condition, requiring strict glycemic control due to rapid physiological changes that affect insulin sensitivity. Continuous glucose monitoring (CGM) provides detailed glucose trends, but the accuracy of newer, affordable systems such as Dexcom One Plus and FreeStyle Libre 2 Plus has not been evaluated during pregnancy.

This prospective interventional study aims to compare the accuracy of these two CGM systems-both worn simultaneously-using capillary glucose as the reference. The study also evaluates educational needs, skills, attitudes, digital competence, lifestyle habits, and patient-reported outcomes among pregnant women with type 1 diabetes (T1D), type 2 diabetes (T2D), and gestational diabetes (GDM).

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Women with diabetes during pregnancy experience increased risks of congenital malformations, neonatal morbidity, hypertensive disorders, and abnormal fetal growth. Continuous glucose monitoring (CGM) improves glycemic outcomes in type 1 diabetes (T1D) in pregnancy, yet evidence remains limited for type 2 diabetes (T2D) and gestational diabetes (GDM). Dexcom One Plus and FreeStyle Libre 2 Plus are recent low-cost systems with CE-mark approval for use in pregnancy, both with reported Mean Absolute Relative Difference (MARD) values around 8%. However, neither system has been specifically validated in pregnant populations.

Physiological changes in pregnancy-including increased total body water and interstitial fluid-may alter CGM accuracy. Prior studies show that earlier FreeStyle Libre versions may overestimate hypoglycemia in pregnant women. Furthermore, women with T2D or GDM typically have little prior exposure to diabetes education or CGM technology, which may contribute to suboptimal glycemic control.

This study evaluates the accuracy and usability of Dexcom One Plus and FreeStyle Libre 2 Plus during pregnancy, while also assessing educational and digital literacy needs to optimize CGM implementation in real-world clinical practice.

Study Type

Interventional

Enrollment (Estimated)

66

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Spain
    • Barcelona
      • Terrassa, Barcelona, Spain, 08221
        • Hospital Universitari Mutua Terrassa

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Pregnant women with type 1 diabetes, type 2 diabetes, or gestational diabetes, diagnosed before 32 weeks of gestation
  • Age ≥18 years
  • Willingness to wear two CGM systems simultaneously
  • Possession of a smartphone compatible with LibreLink
  • Ability to sign informed consent

Exclusion Criteria:

  • Comorbidities affecting glucose metabolism
  • Inability to use CGM devices or perform capillary glucose testing

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Dual Continuous Glucose Monitoring Use
All participants will wear two continuous glucose monitoring sensors simultaneously
Device: Dexcom One Plus
Worn on the upper arm for 10 days Two replacements during the 30-day study period Used with Dexcom mobile application
Device: FreeStyle Libre 2 Plus
Worn on the opposite arm for 15 days One replacement during the 30-day study period Used as real-time CGM via LibreLink
Procedure: Additional Study Procedures
Capillary glucose monitoring before meals, 1 hour postprandially, and during symptoms of hypoglycemia (Contour Instant) One baseline structured education session for participants without prior CGM experience Routine diabetes education according to national guidelines

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean Absolute Relative Difference (MARD)
Time Frame: End of 30-day monitoring period; Primary outcome
Difference between paired continuous glucose monitoring (CGM) readings (Dexcom One Plus vs. FreeStyle Libre 2 Plus) and reference capillary glucose values.
End of 30-day monitoring period; Primary outcome
Baseline diabetes knowledge, skills, and attitudes
Time Frame: Baseline (first study visit)
For the baseline evaluation, a specific questionnaire for the present study was administered, and the Spanish version of the Cambados Questionnaire will also be used. The Cambados Questionnaire is a 5-item questionnaire designed to assess digital competence. The score range is from 0 to 20. Higher scores indicate greater digital competence.
Baseline (first study visit)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean Absolute Difference (MAD) for glucose <70 mg/dL
Time Frame: End of 30-day monitoring period
|Difference| between paired values.
End of 30-day monitoring period
Agreement rates (15/15%, 20/20%, 40/40%) across glucose ranges
Time Frame: End of 30-day monitoring period
Categories: <63, 63-140, <70, 70-180, >140, >180 mg/dL.
End of 30-day monitoring period
Dietary habits (Mediterranean diet adherence)
Time Frame: Baseline and End of 30-day monitoring period
The Mediterranean Diet Adherence Screener (MEDAS) will be used to evaluate adherence to the Mediterranean diet using a 17-item dietary assessment (score range: 0-17). Higher scores indicate greater adherence to the Mediterranean diet.
Baseline and End of 30-day monitoring period
Physical activity
Time Frame: 7 days before baseline and through study completion, an average of 1 week
Physical activity will be assessed by steps per day (measured as total steps) and using the reduced version of the Pregnancy Physical Activity Questionnaire (PPAQ). The reported time spent in each activity category will be multiplied by the established categorical intensity value (METs) associated with that question. The total weekly physical activity level (MET-minutes/week or MET-hours/week) will be calculated by summing the MET values for each item, allowing for classification by intensity (sedentary, light, moderate, and vigorous)
7 days before baseline and through study completion, an average of 1 week
Sleep quality
Time Frame: Baseline and through study completion, an average of 1 week
Pittsburgh Sleep Quality Index (PSQI). The PSQI is a 19-item, self-rated questionnaire designed to measure sleep quality and disturbance. Sleep component scores will be summed to yield a total score ranging from 0 to 21 with the higher total score (referred to as global score) indicating worse sleep quality
Baseline and through study completion, an average of 1 week
Patient-reported outcomes (PROMs)
Time Frame: Through study completion, an average of 1 week
The Glucose Monitoring System Satisfaction Survey (GMSS) will be used to assess patients' satisfaction with their continuous glucose monitoring (CGM) system. GMSS is a 15-item questionnaire with a score range of 1 to 5. Higher scores indicate greater satisfaction.
Through study completion, an average of 1 week

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hospital Mutua de Terrassa

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

December 1, 2025

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

January 1, 2027

Study Registration Dates

First Submitted

November 19, 2025

First Submitted That Met QC Criteria

December 4, 2025

First Posted (Actual)

December 8, 2025

Study Record Updates

Last Update Posted (Actual)

December 8, 2025

Last Update Submitted That Met QC Criteria

December 4, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • P/25-041

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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