Capillary OGTT Study (CapOGTT)

University of Oxford

Status: Enrolling

Conditions: Type 1 Diabetes (T1D)

Study type: Observational

Funder types: Other

Identifiers

NCT06815081

PID16905

Details and patient eligibility

About

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. Early diagnosis 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.

This study aims to test whether an OGTT using a finger-prick to test glucose, can be done at home. This is the 'GTT@home'. The finger-prick creates a drop of blood, which is done before and two hours after drinking a sugary drink. Investigators will also explore whether a continuous glucose monitor (CGM), which reads glucose levels through the skin could be an alternative. The investigators 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, the investigators 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. The investigators will recruit individuals who are having an OGTT as part of a research study, for clinical care, or if individuals 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.

Group 2 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 investigators to understand if the GTT@home can be used in routine care.

Enrollment: 90 estimated patients

Sex: All

Ages: Under 17 years old

Volunteers: Accepts Healthy Volunteers

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

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

Trial design

90 participants in 4 patient groups

Cohort 1 (Simultaneous venous and capillary OGTT)

Description:

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)

Description:

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)

Description:

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

Description:

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.