Capillary OGTT Study (CapOGTT)

April 7, 2026 updated by: University of Oxford

A Study to Determine a Capillary Alternative to the Gold Standard Oral Glucose Tolerance Test

Type 1 diabetes (T1D) is a chronic condition, affecting 1 in 490 children under the age of 15 years. It is caused by the immune system damaging the pancreas, the organ which makes insulin. T1D has recognised stages before symptoms develop, providing an opportunity for early diagnosis, education and treatment which may delay the onset of symptoms.

Type 2 diabetes (T2D) is also a chronic condition where the body cannot make enough insulin, or cannot respond to the insulin properly. It is usually related to obesity, rather than an immune problem. It is more common in adults, but the early stages often start in childhood (up to 1 in 4 children in some clinics). Like T1D, early detection can delay onset of T2D, or even prevent it altogether.

Early diagnosis of T1D or T2D often relies on a test called the oral glucose tolerance test (OGTT), which is commonly used but not well tolerated, possibly because it requires a drip inserted into the vein, and several blood samples taken over 2-3 hours in a healthcare setting.

Our study aims to test whether we can do an OGTT using a finger-prick to test glucose, at home. We call this the 'GTT@home'. The finger-prick creates a drop of blood, which is done before and two hours after drinking a sugary drink. We will also explore whether a continuous glucose monitor (CGM), which reads glucose levels through the skin could be an alternative. We plan to recruit 90 children and young people, across two groups to assess the GTT@home.

To understand the experiences of those involved in monitoring, we will invite young people, parents and healthcare workers to take part in an interview, to understand the impact of testing to predict clinical T1D.

Group 1 will assess the accuracy of measuring glucose from a finger-prick blood test when compared to a blood test from the vein. We will recruit individuals who are having an OGTT as part of a research study, for clinical care or if they have agreed to have an OGTT for this study. Those with T1D will be invited to wear a CGM to explore its use as an additional, practical alternative.

Groups 2 and 3 will assess how well the GTT@home test works when done at home and how acceptable it is. This will only be offered to those known to be at risk of T1D.

These studies will help us to understand if the GTT@home can be used in routine care.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

135

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 Contact Backup

Study Locations

  • United Kingdom
      • Cardiff, United Kingdom, CF14 4XW
        • Recruiting
        • Noah's Ark Childrens Hospital for Wales
        • Principal Investigator:
          • Ambika Shetty
        • Contact:
      • London, United Kingdom, E1 1FR
        • Recruiting
        • Royal London Barts Health NHS Trust
        • Contact:
        • Principal Investigator:
          • Ruben Willemsen
      • Nottingham, United Kingdom, NG7 2UH
        • Recruiting
        • Nottingham Childrens Hospital
        • Principal Investigator:
          • Rachel Williams
        • Contact:
      • Oxford, United Kingdom, OX3 9DU

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

  • Child

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Cohort 1 - Children < 18 years of age. To get a spread of glucose values, we will aim to recruit approximately equal numbers of participants with normoglycaemia, dysglycaemia and hyperglycaemia.

Cohort 1 CGM sub-study - Children < 18 years of age, who have T1D stage 1, 2 or 3 and undergoing an OGTT in cohort 1.This sub-study will be additional and optional to cohort 1.

Cohort 2 - Children < 18 years of age, who are identified as having stage 1, 2 or 3 T1D will be invited to take part in an OGTT at home.

Cohort 3 - Children < 18 years of age, who are identified as having pre-T2D.

Qualitative sub-study - Young people ≥ 15 years old with T1D stage 1, 2 or recent stage 3 (up to 12 months), who have been involved in metabolic follow-up, will be invited to take part. Parents of a child (of any age) with T1D stage 1, 2 or recent stage 3 will also be invited. Healthcare professionals involved in delivering metabolic follow-up for children with diabetes antibodies will also be invited.

Description

Inclusion criteria:

Cohort 1

  • Willing and able to give informed consent for participation, or assent with parental consent
  • Aged < 18 years old
  • Able to consume oral glucose drink within 10 minutes
  • Undergoing an OGTT, or consent to have one

Cohort 2

  • Positive for two or more islet autoantibodies at any time
  • Willing and able to give informed consent for participation, or assent with parental consent
  • Aged < 18 years old
  • Able to consume oral glucose drink within 10 minutes

CGM sub-study

  • Willing and able to give informed consent for participation, or assent with parental consent
  • Aged < 18 years old
  • Able to consume oral glucose drink within 10 minutes
  • Confirmed to have stage 1, 2 or 3 T1D
  • Participation in Cohort 1

Qualitative sub-study

  • Willing and able to give informed consent for participation, or assent with parental consent Then EITHER
  • A young person positive for two or more islet autoantibodies (15 years old and above) at any time, or parent of a young person who has experienced a metabolic test e.g. OGTT OR
  • A healthcare professional involved in delivering metabolic testing

Cohort 3

  • Prediabetes diagnosis as above
  • Willing and able to give informed consent for participation, or assent with parental consent
  • Aged < 18 years old
  • Able to consume oral glucose drink within 10 minutes

Exclusion Criteria:

Cohort 1

  • Any known haemoglobinopathy
  • Cystic fibrosis related diabetes
  • Non-English speaker

Cohort 2

  • Any known haemoglobinopathy
  • Known clinical diabetes and on treatment
  • Non-English speaker
  • No recent weight available (within 3 months of study visit) and unable to obtain new weight measurement

CGM sub-study

  • Any known haemoglobinopathy
  • Cystic fibrosis related diabetes
  • Non-English speaker
  • Any active skin issue which would prevent the use of a CGM device

Qualitative sub-study

• Non-English speaker

Cohort 3

  • Known clinical diabetes and on treatment
  • Non-English speaker
  • No recent weight available (within 3 months of study visit) and unable to obtain new weight measurement

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

Cohorts and Interventions

Group / Cohort
Cohort 1 (Simultaneous venous and capillary OGTT)

To assess the ability of the capillary OGTT to be a reliable and acceptable alternative to the standard venous OGTT in children, investigators will aim to capture a spread of glucose values across the whole diagnostic range.

This will be undertaken in clinical and research settings, led by either a healthcare professional or research nurse.

Children undergoing a standard venous OGTT will be invited to complete a capillary OGTT. Both venous and capillary samples will be collected at the same time. Investigators will also invite children with stage 3 (clinical) T1D to capture glucose levels in the hyperglycaemic range. These participants will receive a smaller glucose dose for their OGTT (1g/kg, max dose 75g), to attenuate their glucose rise and allow the comparison of clinically meaningful glucose values. Participants will be asked to complete a questionnaire following the OGTT to obtain information about acceptability.
Cohort 2 (Capillary OGTT at home)

In this cohort (running concurrently alongside cohort 1) investigators aim to assess the acceptability and feasibility of a capillary OGTT device in children and young people with early-stage (known stage 1 or 2) T1D.

This will take place in the home of participants, with written and video instructions provided.

Children known to be positive for ≥ 2 IAb will be invited to take part and will be sent a capillary OGTT test kit which will include a glucose drink, lancets and instructions (written and video).

They will fast overnight (from midnight the night before, for a minimum of 8 hours) before completing a 2-hour OGTT using the test kit and instructions provided. Glucose samples will be collected at 0 and 120 minutes. Participants will be asked to complete a questionnaire following completion of the OGTT, to obtain information about acceptability.
Cohort 1 (CGM sub-study)

In this sub-study investigators aim to explore the ability of CGM to be an alternative to the standard venous OGTT. A subgroup of participants in cohort 1 with known T1D (stage 1, 2 or 3) will be invited to wear a CGM sensor for up to 10 days, which will be worn during their OGTT, at home during a standard mixed meal and free-living.

Whilst wearing the CGM at home, participants will be asked to consume a liquid mixed meal (Ensure Plus, 6ml/kg maximum 360ml, preceded by an 8-hour fast) and complete a 3-day food diary, by photographing the largest meal of the day to allow estimation of carbohydrate intake (not the same day as the OGTT or liquid mixed meal). Participants will then be asked to complete a questionnaire to obtain information about acceptability.
Qualitative sub-study
To understand the factors that contribute to uptake of monitoring offered to children at risk of type 1 diabetes, investigators will invite a small number of young people (aged 15-18) and parents to take part in a semi-structured interview. Investigators will also invite healthcare professionals involved in delivering metabolic testing as part of follow-up to take part in semi-structured interviews, to understand their views on the factors which may influence future implementation into clinical care.
Cohort 3 (Pre-clinical type 2 diabetes)

In this cohort (running concurrently alongside cohort 1) we aim to assess the acceptability and feasibility of a capillary OGTT device in children with pre-clinical T2D at home.

This will take place in the home of participants, with written or video instructions provided.

For cohort 3, children with raised BMI (≥91st centile) and any marker of insulin resistance: HbA1c 39-47mmol, or known impaired fasting glucose (5.6 - 6.9 mmol/L), or impaired glucose tolerance (7.8 - 11.0 mmol/L), will be invited to take part.

They will fast overnight (from midnight the night before, for a minimum of 8 hours) before completing a 2-hour OGTT using the test kit and instructions provided. Participants will be asked to complete a questionnaire following completion of the OGTT, to obtain information about acceptability.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To determine the agreement of capillary blood glucose levels to venous blood glucose levels during a standard OGTT
Time Frame: From enrolment to end of study visit on day 1.
Agreement between capillary and blood glucose measures.
From enrolment to end of study visit on day 1.
To assess the feasibility of using the capillary OGTT device in the home environment
Time Frame: From enrolment to end of study visit on day 1
  1. Proportion of successful glucose readings at 0, 120 minutes
  2. Proportion of errors/missing glucose readings
  3. Proportion of adverse events
From enrolment to end of study visit on day 1

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To determine the diagnostic accuracy of capillary blood glucose levels at diagnostic thresholds
Time Frame: From enrolment to end of study visit on day 1.
Sensitivity and specificity of capillary glucose at 5.6mmol/L, 7.0mmol/L (fasting), 11.1 mmol/L (60 min), and 7.8mmol/L and 11.1mmol/L (120 min).
From enrolment to end of study visit on day 1.
Assess the acceptability of the capillary OGTT device
Time Frame: From enrolment to end of study visit on day 1.
Acceptability by questionnaire (Parent +/- child), using either a standard 7-point Likert scale (1 - not painful at all, 7 - very painful) for participants aged 16 and above, or Wong Baker Faces pain scale (0 - no hurt, 10 - hurts worst) for participants aged under 16.
From enrolment to end of study visit on day 1.
To assess the in-depth experience of participants attending study visits involving a metabolic test or assessment
Time Frame: From enrolment to end of study visit on day 1
Analysis of qualitative interviews from young people.
From enrolment to end of study visit on day 1
To assess the in-depth experience of parents attending study visits with their child involving a metabolic test or assessment
Time Frame: From enrolment to end of study visit on day 1.
Analysis of qualitative interviews from parents.
From enrolment to end of study visit on day 1.
To assess the in-depth views of healthcare professionals involved in the delivery of a metabolic test or assessment of a child
Time Frame: From enrolment to end of study visit on day 1.
Analysis of qualitative interviews from healthcare professionals.
From enrolment to end of study visit on day 1.

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
To explore the diagnostic accuracy of CGM to define T1D stages during a standard OGTT
Time Frame: From enrolment to end of study visit at day 10.
Sensitivity/specificity of sensor glucose levels at diagnostic thresholds.
From enrolment to end of study visit at day 10.
To explore CGM values at fasting and 120-minutes and its relation to OGTT measures of glucose, during a) standard liquid mixed meal, and b) free-living
Time Frame: From enrolment to end of study visit on day 10.
Sensor glucose variability (coefficient of variation (%CV)), during home meals, across different T1D stages.
From enrolment to end of study visit on day 10.
To explore CGM values at fasting and 120-minutes and its relation to OGTT measures of glucose, during a) standard liquid mixed meal, and b) free-living
Time Frame: From enrolment to end of study visit on day 10.
Sensor glucose variability (mean amplitude of glycaemic excursion (MAGE) mmol/L)), during home meals, across different T1D stages.
From enrolment to end of study visit on day 10.
To explore CGM values at fasting and 120-minutes and its relation to OGTT measures of glucose, during a) standard liquid mixed meal, and b) free-living
Time Frame: From enrolment to end of study visit on day 10.
Sensor glucose variability (low blood glucose index (LBGI)), during home meals, across different T1D stages.
From enrolment to end of study visit on day 10.
To explore CGM values at fasting and 120-minutes and its relation to OGTT measures of glucose, during a) standard liquid mixed meal, and b) free-living
Time Frame: From enrolment to end of study visit on day 10.
Sensor glucose variability (high blood glucose index (HBGI)), during home meals, across different T1D stages.
From enrolment to end of study visit on day 10.
To explore CGM values at fasting and 120-minutes and its relation to OGTT measures of glucose, during a) standard liquid mixed meal, and b) free-living
Time Frame: From enrolment to end of study visit on day 10.
Sensor glucose variability (average daily risk range (ADRR)), during home meals, across different T1D stages.
From enrolment to end of study visit on day 10.

Collaborators and Investigators

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

Sponsor

University of Oxford

Collaborators

Yale University
Nottingham University Hospitals NHS Trust
University of Bristol
Cardiff and Vale University Health Board
Oxford University Hospitals NHS Trust
Royal London Hospital, Barts Health NHS Trust

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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 (Actual)

February 29, 2024

Primary Completion (Estimated)

February 28, 2027

Study Completion (Estimated)

August 31, 2027

Study Registration Dates

First Submitted

January 27, 2025

First Submitted That Met QC Criteria

February 4, 2025

First Posted (Actual)

February 7, 2025

Study Record Updates

Last Update Posted (Actual)

April 13, 2026

Last Update Submitted That Met QC Criteria

April 7, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PID16905

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Dates of birth will not be shared, but ages (possibly grouped) will be provided.

IPD Sharing Time Frame

IPD and supporting information will be availabile once the primary paper for the study has been published.

IPD Sharing Access Criteria

Subject to participant consent, data will be shared with other researchers for research projects that have appropriate ethical approval. Requests for access to the data will be controlled by the Data Access Committee.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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