Continuous Glucose Monitoring, Pregestational Diabetes
Conditions
Keywords
type 2 diabetes, continuous glucose monitoring, pregnancy
Brief summary
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).
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.
Interventions
DEVICEDexcom One Plus
Worn on the upper arm for 10 days Two replacements during the 30-day study period Used with Dexcom mobile application
DEVICEFreeStyle 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
PROCEDUREAdditional 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
Sponsors
Hospital Mutua de Terrassa
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Intervention model description
All participants receive both sensors simultaneously
Eligibility
Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Mean Absolute Relative Difference (MARD) | 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. |
| Baseline diabetes knowledge, skills, and attitudes | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Dietary habits (Mediterranean diet adherence) | 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. |
| Physical activity | 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) |
| Mean Absolute Difference (MAD) for glucose <70 mg/dL | End of 30-day monitoring period | \|Difference\| between paired values. |
| Patient-reported outcomes (PROMs) | 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. |
| Sleep quality | 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 |
| Agreement rates (15/15%, 20/20%, 40/40%) across glucose ranges | End of 30-day monitoring period | Categories: \<63, 63-140, \<70, 70-180, \>140, \>180 mg/dL. |
Countries
Spain
Contacts
Primary ContactVerónica Perea, MD, PhD
Outcome results
None listed