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.
Adults aged 18-70 years.
BMI ≥ 27 kg/m² (overweight or obese).
Stable body weight (±3 kg) in the last 3 months.
No current use of antidiabetic or weight-loss medications.
Diagnosis of type 1 or type 2 diabetes mellitus (fasting glucose ≥ 7.0 mmol/L or HbA1c ≥ 6.5%).
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).
Crossover
Continuous Glucose Monitoring (CGM)
DeviceUse 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.
Change in Glycemic Variability Assessed by Coefficient of Variation from CGM
Change in glucose coefficient of variation (CV%), calculated from CGM data, comparing open versus blinded CGM phases. Unit of Measure: Percentage (%)
Postprandial Glucose Excursions Measured by CGM
Mean postprandial glucose excursion (PPGE) following habitual meals, derived from CGM data. Unit of Measure: mmol/L
Change in Mean Daily Energy Intake
Change in mean daily caloric intake assessed using participant-completed food diaries. Unit of Measure: kcal/day
Change in Time in Tight Range (3.9-7.8 mmol/L) Measured by Continuous Glucose Monitoring
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 (%)
Change in Glycemic Variability Assessed by Standard Deviation from CGM
Change in standard deviation of interstitial glucose values derived from CGM data, comparing open versus blinded CGM phases. Unit of Measure: mmol/L
Change in Continuous Overall Net Glycemic Action (CONGA) from CGM
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
Change in Glycemic Complexity Assessed by Entropy-Based Indices from CGM
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
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University of Primorska
Lead sponsor
Diabetes Outpatient Clinic, Community Health Center Koper, Slovenia
Collaborator
University Medical Centre Ljubljana
Collaborator
