Clinical trial NCT06862128: OGTT At Home Using CGM Vs At the Clinic
Official title: Oral Glucose Tolerance Test At Home with Continuous Glucose Monitoring Vs Standard Clinic-based Testing
Study type: INTERVENTIONAL
Overall status: NOT_YET_RECRUITING
Phase: NA
Conditions: Pre-diabetes
Diabetes
Keywords: Pre-diabetes
Diabetes
Oral glucose tolerance test
Continuous glucose monitoring
Glucose
Lead sponsor: Linkoeping University
Sponsor class: OTHER_GOV
Collaborators: name: Region Jönköping County
name: Region Östergötland
First posted: 2025-03-06
Enrollment: 75
Sex: ALL
Minimum age (years): 18
Maximum age (years): 70
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: DIAGNOSTIC

Brief summary: This randomized, crossover study evaluates the feasibility and accuracy of a self-administered oral glucose tolerance test (OGTT) at home using continuous glucose monitoring (CGM) compared to a standard clinic-based OGTT. Participants with prediabetes will undergo both home-based and clinic-based OGTTs, with glucose levels measured via CGM and venous plasma glucose. The primary outcome is the correlation between CGM-based glucose values and standard OGTT results. Secondary outcomes include diagnostic agreement, metabolic hormone associations, and feasibility of home-based testing as a diagnostic tool for dysglycemia.

Detailed description: This study aims to evaluate the feasibility, accuracy, and diagnostic utility of a self-administered oral glucose tolerance test (OGTT) at home using continuous glucose monitoring (CGM) compared to a standard clinic-based OGTT.

Study Design Type: Randomized, crossover study Participants: 75 adults with prediabetes Intervention: Each participant will complete both a home-based OGTT with CGM and a clinic-based OGTT with venous plasma glucose measurement.

Primary Objective To assess the correlation between glucose values obtained from a CGM-based home OGTT and a standard venous OGTT performed in the clinic.

Secondary Objectives Evaluate diagnostic agreement between CGM-derived and venous glucose measurements.

Assess variability in glucose responses between the two methods. Investigate associations between OGTT results and metabolic/sex hormones. Determine feasibility and patient adherence to home-based testing.

Methods Participants will be randomized into two groups: one starting with a clinic-based OGTT, the other with a home-based OGTT, followed by a crossover period. CGM will continuously monitor glucose responses, and standard venous plasma glucose measurements will serve as the reference method.

Clinical Relevance A validated home-based OGTT using CGM could improve access to glucose tolerance testing, reduce patient burden, and enhance early detection of dysglycemia.

Eligibility criteria: Inclusion Criteria:

* Prediabetes indicated by both of the following in the past 2 years:
* - ≥1 fasting venous plasma glucose ≥6.1 but ≤6.9 mmol/L OR ≥1 non-fasting venous plasma glucose ≥7.8 but ≤11.0 mmol/L
* - ≥1 HbA1c ≥39 but ≤47 mmol/mol
* Use of GLP-1 receptor agonists or SGLT-2 inhibitors
* Access to a smart phone which is compatible with the CGM application and has working Bluetooth connectivity
* Ability to read and respond to online instructions and questionnaires in Swedish.

Exclusion Criteria:

* Previous oral glucose tolerance test (OGTT)
* T2D indicated by any of the following at any time:
* - Fasting venous plasma glucose ≥7.0 mmol/L
* - Non-fasting venous plasma glucose value ≥11.1 mmol/L
* - HbA1c ≥48 mmol/mol
* Previous bariatric surgery e.g., gastric by-pass or gastric sleeve surgery
* Body mass index \<25 kg/m2, indicating an increased risk of type 1-diabetes, maturity-onset diabetes of the young or latent autoimmune diabetes in adults
* Body weight \<43 kg, which is a contraindication to administer the full OGTT glucose solution according to Swedish guidelines
* Current pregnancy, because gestational diabetes is a unique entity
* Need of regular use of acetaminophen or ascorbic acid supplements during the study period, which may interfere with CGM accuracy33
* Fear of needle sticks
* Involvement in the study design, data collection, analysis, or participant recruitment.

Primary outcomes:
measure: The correlation coefficient between the glucose levels of the OGTT-home vs OGTT-clinic
timeFrame: Between OGTT-clinic at baseline vs OGTT-home at each 5-min interval from 0-30 min; Between OGTT-clinic at 1 h vs OGTT-home at each 5-min interval from 60-90 min; Between OGTT-clinic at 2 h vs OGTT-home at each 5-min interval from 120-150 min
measure: The sensitivity and specificity, as well as the positive and negative predictive values of the OGTT at home vs the OGTT at the clinic
timeFrame: At 1 and 2 hours after the start of the OGTT
Secondary outcomes:
measure: The sensitivity, specificity, positive and negative predictive value of the highest OGTT-home vs OGTT-clinic
timeFrame: Any of the values from 5-minute intervals 0-150 minutes of OGTT-home vs OGTT-clinic at 1 and 2 hours, respectively
measure: The sensitivity, specificity, positive and negative predictive value of the highest CGM value vs OGTT-clinic
timeFrame: Any of the values from 5-minute intervals days 1-14 of the CGM vs OGTT-clinic at 1 and 2 hours, respectively
Other outcomes:
Locations:
city: Huskvarna
country: Sweden
facility: Primary Health Care Center Bra Liv Rosenhälsan
state: Jönköping County
city: Norrköping
country: Sweden
facility: Primary Health Care Center Cityhälsan Centrum
city: Linköping
country: Sweden
facility: Primary Care Center Vårdcentralen Kärna
state: Östergötland County
Study officials:
affiliation: Linkoeping University
name: Peder af Geijerstam, MD, PhD
role: PRINCIPAL_INVESTIGATOR
References: