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NCT Number: NCT06815081

Capillary OGTT Study

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.

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Key information

Conditions

Type 1 Diabetes (T1D) Autoimmune Diseases Diabetes Mellitus Diabetes Mellitus, Type 1 Diabetes Mellitus, Type 2 Endocrine System Diseases Glucose Metabolism Disorders Immune System Diseases Metabolic Diseases Nutritional and Metabolic Diseases Type 2 Diabetes

Age range

Up to 17 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Noah's Ark Childrens Hospital for Wales, Cardiff, United Kingdom

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Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Primary outcomes

  1. 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.

  2. 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

    • Proportion of successful glucose readings at 0, 120 minutes
    • Proportion of errors/missing glucose readings
    • Proportion of adverse events

Secondary outcomes

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

Other outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Claire Scudder

CONTACT

[email protected]

+44 (0)7765 932065

Rabbi Swaby, BMBS

CONTACT

[email protected]

+44 1865287578

Sponsors and collaborators

Lead sponsor

University of Oxford

Other

Collaborators

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

Registry information

Official study title

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

Acronym: CapOGTT

Important dates

Study start
2024
Primary completion
2027
Study completion
2027
First posted
Feb 7, 2025
Registry last updated
Apr 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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