CGM Accuracy in Pregnancy Study

Official title

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

Overview

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

• 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

Primary outcome measures

• Mean Absolute Relative Difference (MARD) [Time frame: End of 30-day monitoring period; Primary outcome]
• Baseline diabetes knowledge, skills, and attitudes [Time frame: Baseline (first study visit)]

Secondary outcome measures (6)

• Mean Absolute Difference (MAD) for glucose <70 mg/dL [Time frame: 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]
• Dietary habits (Mediterranean diet adherence) [Time frame: 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]
• Sleep quality [Time frame: Baseline and through study completion, an average of 1 week]
• Patient-reported outcomes (PROMs) [Time frame: Through study completion, an average of 1 week]

Eligibility criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Diagnostic

Study locations

Spain · 1 center

• Hospital Universitari Mutua Terrassa — Terrassa

Publications

• Driesman AS, Konopka JA, Feder O, Aggarwal V, Schwarzkopf R. Management Principles of Massive Acetabular Bone Loss in Revision Total Hip Arthroplasty A Review of the Literature. Bull Hosp Jt Dis (2013). 2023 Mar;81(1):4-10. PMID 36821729
• Dai J, Liu D, Yin X, Wen X, Cai G, Zheng L. Anisotropic Elastomer Ionomer Composite-Based Strain Sensors: Achieving High Sensitivity and Wide Detection for Human Motion Detection and Wireless Transmission. ACS Sens. 2024 Apr 26;9(4):2156-2165. doi: 10.1021/acssensors.4c00274. Epub 2024 Apr 17. PMID 38629405
• Lin S, Pan X, Meng D, Zhang T. Electric conversion treatment of cobalt-containing wastewater. Water Sci Technol. 2021 Apr;83(8):1973-1986. doi: 10.2166/wst.2021.101. PMID 33905366
• Kawada T. Psychosocial factors and mortality in patients with heart failure. Eur J Heart Fail. 2018 Aug;20(8):1243. doi: 10.1002/ejhf.1208. Epub 2018 Apr 24. No abstract available. PMID 29693755
• Murphy HR, Howgate C, O'Keefe J, Myers J, Morgan M, Coleman MA, Jolly M, Valabhji J, Scott EM, Knighton P, Young B, Lewis-Barned N; National Pregnancy in Diabetes (NPID) advisory group. Characteristics and outcomes of pregnant women with type 1 or type 2 diabetes: a 5-year national population-based cohort study. Lancet Diabetes Endocrinol. 2021 Mar;9(3):153-164. doi: 10.1016/S2213-8587(20)30406-X. PMID 33516295
• Simmons D, Immanuel J, Hague WM, Teede H, Nolan CJ, Peek MJ, Flack JR, McLean M, Wong V, Hibbert E, Kautzky-Willer A, Harreiter J, Backman H, Gianatti E, Sweeting A, Mohan V, Enticott J, Cheung NW; TOBOGM Research Group. Treatment of Gestational Diabetes Mellitus Diagnosed Early in Pregnancy. N Engl J Med. 2023 Jun 8;388(23):2132-2144. doi: 10.1056/NEJMoa2214956. Epub 2023 May 5. PMID 37144983

Identifiers

NCT: NCT07269015 · P/25-041

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗