The Impact of Continuous Glucose Monitoring on Glucose Variability and Weight Loss in Individuals With Prediabetes and Obesity (CGM)

April 27, 2026 updated by: Zala Jenko Praznikar, University of Primorska

The Impact of Continuous Glucose Monitoring on Behavioral Change, Glucose Variability and Weight Loss in Individuals With Prediabetes and Obesity - a Randomized Crossover Study

This randomized, crossover interventional study evaluates the effects of real-time (open) versus blinded continuous glucose monitoring (CGM) on glycemic variability, lifestyle behaviors, and metabolic outcomes in adults with prediabetes and overweight or obesity (BMI ≥ 27 kg/m²). Thirty participants will undergo both open and blinded CGM phases, separated by a washout period. The study aims to assess whether access to real-time glucose data promotes behavioral change and improves metabolic health compared with blinded CGM use.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Prediabetes and obesity are major contributors to the development of type 2 diabetes and its complications. Early intervention focused on glycemic control and lifestyle modification is essential to prevent disease progression. Continuous glucose monitoring (CGM) provides real-time insight into glucose dynamics and may support behavioral change; however, evidence is limited on how access to glucose data influences sustained lifestyle modification and metabolic outcomes in individuals with prediabetes.

The primary objectives are to assess the impact of real-time (open) versus blinded CGM on (1) glycemic variability using sensitive dynamic metrics, and (2) behavioral changes, including dietary habits and physical activity, in adults with prediabetes and overweight or obesity.

Secondary objectives include evaluating the effects of CGM on anthropometric and metabolic parameters, biochemical and physiological markers of metabolic control, participant experience and acceptability of CGM, sustainability of lifestyle changes, and associations between glycemic variability and cardiometabolic risk reduction.

This prospective, randomized, open-label, blinded crossover interventional study will evaluate the effects of CGM on behavior, glycemic variability, and weight loss in adults with prediabetes and obesity (BMI ≥ 27 kg/m²). Thirty participants will be recruited from the Diabetes Outpatient Clinic of the Community Health Center Koper. After screening and a 10-day blinded CGM run-in period, participants will be randomized (1:1) to one of two sequences: (A) open CGM for 12 weeks followed by a 30-day washout and 12 weeks of blinded CGM, or (B) blinded CGM for 12 weeks followed by washout and 12 weeks of open CGM. Participants will attend baseline and follow-up visits for anthropometric, biochemical, and behavioral assessments during each study phase.

Study Type

Interventional

Enrollment (Estimated)

34

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

  • Slovenia
      • Izola, Slovenia, 6310
        • Recruiting
        • University of Primorska, Faculty of Health Sciences
        • Contact:
        • Contact:
          • Ana Petelin, PhD
      • Koper, Slovenia, 6000
        • Recruiting
        • Diabetes Outpatient Clinic, Community Health Center Koper, Slovenia
        • Contact:
      • Ljubljana, Slovenia, 1000
        • Recruiting
        • Department Of endocrinology and diabetes, Medical Faculty, University of Ljubljana
        • Contact:

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:

  • Adults aged 18-70 years.
  • BMI ≥ 27 kg/m² (overweight or obese).
  • Prediabetes, confirmed by:

Impaired fasting glucose (IFG: 5.6-6.9 mmol/L), and/or Impaired glucose tolerance (IGT: 2-hour OGTT glucose 7.8-11.0 mmol/L).

  • Stable body weight (±3 kg) in the last 3 months.
  • No current use of antidiabetic or weight-loss medications.
  • Willingness and ability to wear a CGM device as instructed.
  • Capacity to provide written informed consent.
  • Recruitment from the Diabetes Outpatient Clinic, Community Health Center Koper (identified and invited from the clinic's database).

Exclusion Criteria:

  • Diagnosis of type 1 or type 2 diabetes mellitus (fasting glucose ≥ 7.0 mmol/L or HbA1c ≥ 6.5%).
  • Current or recent (within 3 months) use of:
  • Any antidiabetic medication (insulin, metformin, GLP-1RA, SGLT2i, etc.), or anti-obesity pharmacotherapy.
  • Pregnancy, breastfeeding, or planned pregnancy during the study period.
  • Severe chronic disease that could influence glucose metabolism or study participation (e.g., chronic liver disease, renal failure, active malignancy).
  • Endocrine disorders affecting metabolism (e.g., untreated thyroid disease, Cushing's syndrome).
  • Severe psychiatric illness or cognitive impairment limiting adherence or comprehension.
  • Use of medications known to affect glucose metabolism (e.g., corticosteroids, atypical antipsychotics).
  • Implanted electronic medical devices (e.g., pacemaker, defibrillator) that may interfere with CGM function.
  • Known allergy or skin reaction to CGM adhesives or device materials.
  • Participation in another interventional study within the previous 3 months.

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Open CGM
Device: Continuous Glucose Monitoring (CGM)
Use of a continuous glucose monitoring system to measure interstitial glucose levels. During the open CGM phase, participants have real-time access to glucose data; during the blinded CGM phase, glucose data are masked from participants.
Experimental: Blinded CGM
Device: Continuous Glucose Monitoring (CGM)
Use of a continuous glucose monitoring system to measure interstitial glucose levels. During the open CGM phase, participants have real-time access to glucose data; during the blinded CGM phase, glucose data are masked from participants.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Glycemic Variability Assessed by Coefficient of Variation from CGM
Time Frame: End of each 12-week CGM phase
Change in glucose coefficient of variation (CV%), calculated from CGM data, comparing open versus blinded CGM phases. Unit of Measure: Percentage (%)
End of each 12-week CGM phase
Postprandial Glucose Excursions Measured by CGM
Time Frame: End of each 12-week CGM phase
Mean postprandial glucose excursion (PPGE) following habitual meals, derived from CGM data. Unit of Measure: mmol/L
End of each 12-week CGM phase
Change in Mean Daily Energy Intake
Time Frame: End of each 12-week CGM phase
Change in mean daily caloric intake assessed using participant-completed food diaries. Unit of Measure: kcal/day
End of each 12-week CGM phase

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Time in Tight Range (3.9-7.8 mmol/L) Measured by Continuous Glucose Monitoring
Time Frame: End of each 12-week CGM phase
Change in percentage of time glucose values are within the tight range of 3.9-7.8 mmol/L, derived from continuous glucose monitoring (CGM) data, comparing open versus blinded CGM phases. Unit of Measure: Percentage (%)
End of each 12-week CGM phase
Change in Glycemic Variability Assessed by Standard Deviation from CGM
Time Frame: End of each 12-week CGM phase
Change in standard deviation of interstitial glucose values derived from CGM data, comparing open versus blinded CGM phases. Unit of Measure: mmol/L
End of each 12-week CGM phase
Change in Continuous Overall Net Glycemic Action (CONGA) from CGM
Time Frame: End of each 12-week CGM phase
Change in CONGA index calculated from CGM glucose profiles, reflecting short-term glycemic variability, comparing open versus blinded CGM phases. Unit of Measure: mmol/L
End of each 12-week CGM phase
Change in Glycemic Complexity Assessed by Entropy-Based Indices from CGM
Time Frame: End of each 12-week CGM phase
Change in glucose pattern complexity assessed using entropy-based indices derived from CGM data, comparing open versus blinded CGM phases. Unit of Measure: Unitless index
End of each 12-week CGM phase
Postprandial Incremental Area Under the Curve (iAUC) Derived from CGM
Time Frame: End of each 12-week CGM phase
Incremental area under the glucose curve (iAUC) following habitual meals, calculated from CGM data. Unit of Measure: mmol/L·min
End of each 12-week CGM phase
Adherence to Continuous Glucose Monitoring
Time Frame: End of each 12-week CGM phase
Adherence to CGM use, defined as percentage of days with valid CGM data and frequency of data uploads. Unit of Measure: Percentage (%)
End of each 12-week CGM phase
Change in Fasting Plasma Glucose
Time Frame: Baseline; end of each 12-week CGM phase
Change in Fasting Plasma Glucose measured in mmol/L by biochemical analyzer.
Baseline; end of each 12-week CGM phase
Change in Body Weight
Time Frame: Baseline; end of each 12-week CGM phase
Change in Body Weight (in kg) from baseline to week twelve (of each CGM phase).
Baseline; end of each 12-week CGM phase
Change in Physical Activity Assessed by IPAQ Short Form
Time Frame: Baseline; end of each 12-week CGM phase
Physical activity assessed using the International Physical Activity Questionnaire (IPAQ) short form, reported as total MET-minutes per week.
Baseline; end of each 12-week CGM phase
Change in Health Status Assessed by EQ-VAS
Time Frame: Baseline; end of each 12-week CGM phase
Change in Health Status Assessed by EQ-VAS index score (0-100; higher scores indicate better perceived health).
Baseline; end of each 12-week CGM phase
Change in Glycated Hemoglobin (HbA1c)
Time Frame: Baseline; end of each 12-week CGM phase
Change in Glycated Hemoglobin (HbA1c) measured in % (according to The National Glycohemoglobin Standardization Program - NGSP)
Baseline; end of each 12-week CGM phase

Collaborators and Investigators

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

Sponsor

University of Primorska

Collaborators

University Medical Centre Ljubljana
Diabetes Outpatient Clinic, Community Health Center Koper, Slovenia

Investigators

  • Principal Investigator: Ajda Urbas, MD, Diabetes Outpatient Clinic, Community Health Center Koper, Slovenia
  • Study Chair: Mojca Jensterle Sever, PhD, University Medical Centre Ljubljana, Department Of endocrinology and diabetes, Medical Faculty, University of Ljubljana
  • Study Chair: Zala Jenko Pražnikar, PhD, University of Primorska, Faculty of Health Sciences

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)

September 1, 2026

Primary Completion (Estimated)

April 1, 2027

Study Completion (Estimated)

September 1, 2027

Study Registration Dates

First Submitted

January 26, 2026

First Submitted That Met QC Criteria

February 12, 2026

First Posted (Actual)

February 20, 2026

Study Record Updates

Last Update Posted (Actual)

April 28, 2026

Last Update Submitted That Met QC Criteria

April 27, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CGM

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

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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