OGTT at Home Using CGM vs at the Clinic

Linkoeping University75 enrolled

Overview

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.

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

DIAGNOSTIC

Masking

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Prediabetes indicated by ≥2 of the following values, measured at separate occasions or through different analyses during the past 2 years: * \- Fasting venous plasma glucose ≥6.1 but ≤6.9 mmol/L * \- Non-fasting venous plasma glucose ≥7.8 but ≤11.0 mmol/L * \- HbA1c ≥39 but ≤47 mmol/mol * 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: * T2D indicated by ≥2 of the following values, measured at different occasions or through different analyses: * \- 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 \<20 kg/m2 * Body weight \<43 kg * Current pregnancy * Need of regular use of GLP-1 receptor agonists, SGLT-2 inhibitors, acetaminophen or ascorbic acid supplements during the study period * Fear of needle sticks * Shift work during the study period * Involvement in the study design, data collection, analysis, or participant recruitment.

Locations (3)

Primary Health Care Center Bra Liv Rosenhälsan

Huskvarna, Jönköping County, Sweden

RECRUITING

Primary Health Care Center Cityhälsan Centrum

Norrköping, Norrköping, Sweden

RECRUITING

Primary Care Center Vårdcentralen Kärna

Linköping, Östergötland County, Sweden

RECRUITING

Outcomes

Primary Outcomes

Diagnostic accuracy of the 2-hour CGM glucose value during home-based OGTT compared with 2-hour venous plasma glucose during clinic-based OGTT

The diagnostic accuracy of the 2-hour interstitial glucose measured by CGM during a home-based oral glucose tolerance test (OGTT) will be evaluated against the 2-hour venous plasma glucose obtained during a clinic-based OGTT (reference standard) for the classification of normoglycemia, prediabetes, and diabetes. The 2-hour CGM value will be defined as the first CGM recording at or within 5 minutes after the 2-hour timepoint (i.e., between 120 and 125 minutes). Diagnostic accuracy will be assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Cohen's kappa coefficient for overall classification agreement, each reported with 95% CIs. Systematic bias and limits of agreement between the two continuous glucose measurements will further be assessed using Bland-Altman analysis.

Time frame: 2 hours after the start of the OGTT

Secondary Outcomes

Diagnostic accuracy of the lag-adjusted 2-hour CGM glucose value during home-based OGTT compared with 2-hour venous plasma glucose during clinic-based OGTT

The diagnostic accuracy of a lag-adjusted CGM glucose value during a home-based oral glucose tolerance test (OGTT) will be evaluated against the 2-hour venous plasma glucose during a clinic-based OGTT (reference standard) for the classification of normoglycemia, prediabetes, and diabetes. The lag-adjusted timepoint will be identified from the clinic-based OGTT as the CGM recording between 120 and 140 minutes showing the highest concordance with the 2-hour venous plasma glucose, assessed using Lin's concordance correlation coefficient (CCC), and applied accordingly during the home-based OGTT. Diagnostic accuracy will be assessed using sensitivity, specificity, PPV, NPV, and Cohen's kappa, each with 95% CIs, and Bland-Altman analysis will be used to assess systematic bias and limits of agreement.

Time frame: 0-20 minutes after the 2-hour timepoint of the OGTT (lag-adjusted)

Reproducibility of home-based OGTT using CGM

Reproducibility of the 2-hour CGM glucose value across the two home-based OGTTs will be assessed using intraclass correlation coefficients (ICC), and agreement in glycemic classification (normoglycemia, prediabetes, and diabetes) will be assessed using weighted Cohen's kappa. Both the unadjusted and lag-adjusted 2-hour CGM values will be evaluated.

Time frame: 2 hours and 2 hours plus 0-20 minutes lag-adjustment after the start of the OGTT

OGTT at Home Using CGM vs at the Clinic

Overview

Conditions

Interventions

Eligibility

Locations (3)

Outcomes

Primary Outcomes

Secondary Outcomes

Central Contacts