Glucose Variability in Type 1 Diabetes (T1D) and Glycaemic Responses to Food Composition.

March 14, 2025 updated by: University of Stirling

An Investigation Into Diurnal Variability in Glucose Levels in Paediatric Patients With Type 1 Diabetes (T1D) and Their Responses to Different Food Compositions

The study proposed to recruit approximately 435 children and young people who have T1D and who regularly use Dexcom continuous glucose monitoring (CGM). Recruitment was be via their local dietitian. The dietitian was asked to provide baseline information about the participants which will include demographic data and information on clinical data, treatment and anthropometrics. Participants will be asked to provide access to Dexcom CGM data throughout the period of recording. Participants were issued with, for seven consecutive days, two survey questionnaires, one in the morning at breakfast time and the other in the evening. The morning survey will include questions on the breakfast meal (including a photograph of the meal) and insulin dosage, similarly the evening survey will also include questions on diabetes management and food and fluid intake in addition to questions on activities all of which took place during the four-hour postprandial period. These data will be statistically described using univariate, bivariate and multivariate analysis.

Study Overview

Status

Completed

Conditions

Type 1 Diabetes

Intervention / Treatment

Other: Breakfast

Detailed Description

This is a quantitative observational study. Dexcom CGM data was collected for the period recording. Retrospective CGM data was collected to assess glucose variability during the day and night time periods. The Participants were then asked to provide information for seven days about their breakfast meal and the four hour post meal period. This included information on the type of meal consumed, a photograph of the meal and their diabetes management for the meal for example the insulin dose amount and timing. For the four hour post meal period the participants were asked about any adjustments they had to make to their diabetes management for example the treatment of high or low glucose readings, any snacks they ate and any activities they took part in. They were also asked to describe their mood during the post meal period.

Recruitment - Paediatric diabetes dietitians, working across the United Kingdom (UK), were enrolled to help recruit participants and become principal investigators (PI) for their site.

As this was an observational study there was no power calculation. The sample size was calculated from the number of dietitians that were likely to be available to help with recruitment; this was estimated to be around 32 and was based on the number that had already been approached. It was felt that they would have capacity to recruit 13-14 participants and this would result in 435 participants.

Methodology Baseline data

In order to make comparisons between relevant variables and glucose levels, the following baseline data will be collected from the dietitians and sent to the chief investigator, along with the artificial identifier on the Excel spreadsheet as discussed earlier at the stage of recruitment of participants:

Parent's email address Sex, date of birth and recent weight and height (for calculation of BMI and BMI centile) and date of when this was taken Date of diagnosis of T1D Last four HbA1c Total daily insulin dose (TDD) Insulin: carbohydrate ratios (ICR) and Insulin Sensitivity Factor (ISF) Current insulin regimen - including the type of insulin prescribed and if applicable type of insulin pump i.e. open or closed loop system.

Glucose measurement data on interstitial glucose was be collected via Dexcom CGM. The Dexcom CGM data will be accessed by a research 'Clarity Clinic' with Dexcom CLARITY® Clinic Portal (Dexcom In, San Diego, California (CA), USA). The researcher was the administrator of this clinic. Once the local dietitian had recruited, the participant's parent's email address will be sent to the researcher along with the baseline information/data as described above. The researcher, as administrator of the Clarity Clinic account, then invited the participant, via email, to be added to the clinic. Once the invite has been accepted, it stood for the period of the recording i.e. until all the seven day breakfast recording period was completed. Once the participant had submitted their last questionnaire, they were removed from the Dexcom CLARITY® Clinic Portal.

The participants were not asked to make changes to their diabetes management and their breakfast meal. The participants were asked to submit two daily questionnaires (a morning and post-meal questionnaire) for seven days about their breakfast meal and the postprandial period and email a photograph of the breakfast meal.

The morning questionnaire was about the breakfast meal and included the following questions:

Participant's artificial identifier Date (of when meal was taken) The total average daily insulin dose (both bolus and basal insulin) if known (participant will only be asked to provide this once) Food eaten at breakfast including portion size, type and brand Drinks taken at breakfast including volume, type and brand The total carbohydrate count of breakfast in grams The number of units of insulin taken with breakfast How many units were given for a correction dose The type of bolus (for those on an insulin pump) The time of when the insulin dose was administered The time that breakfast started and ended How the bolus was calculated The amount of breakfast that was consumed (all, ¾, ½, ¼, none)

The post meal questionnaire included the following questions:

Participant's artificial identifier Date (of when meal was taken) Details of any hypo's in the four-hour postprandial period (time, treatment) Details of correction doses given in the four-hour postprandial period (whether in response to Dexcom CGM, times and number of units if insulin) Details of snacks taken in the four-hour postprandial period (type and amount of carbohydrate, responses to Dexcom CGM, number of units of insulin) Details of drinks taken in the four-hour postprandial period (volume, type/brand, carbohydrate amount if applicable) Details of any other adjustments made to insulin and or carbohydrate Type and duration of all physical activities undertaken during the 4-hour post prandial period Details of insulin adjustments made for physical activities Details of any addition information e.g. mood, menstruating, illness, stressors

Data analysis This will be a mix of univariate, bivariate and multivariate analysis as this is best suited to describing, summarising and visualising these data. Outputs will include the distribution of glucose levels post-breakfast to determine the spread and dispersion of the data.

Study Type

Observational

Enrollment (Actual)

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

United Kingdom
- Stirlingshire
  - Stirling, Stirlingshire, United Kingdom, FK9 4LA
    - Faculty of Health Sciences and Sport

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

Sampling Method

Non-Probability Sample

Study Population

Children and young people aged 1-17 who have type 1 diabetes

Description

Inclusion Criteria:

Children and young people aged between 1-17 years
Diagnosis of type 1 diabetes for a minimum of one year
Using multiple daily injections (MDI) together with carbohydrate counting or Continuous Subcutaneous Insulin Infusion (CSII)
Using Dexcom continuous glucose monitoring (CGM) on a regular basis.
Access to internet and email

Exclusion Criteria:

Prescribed anti-hyperglycaemia agents i.e. Glucophage (Metformin) and or antidepressants.
Have other medical conditions, including complications of diabetes and coeliac disease will be excluded.
Currently enrolled in another research study

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Postprandial Glucose Time Frame: From baseline (start of meal) to 4 hours postprandial at 5min intervals	Mean CGM reading for 387 breakfast meals over 4 hour postprandial period	From baseline (start of meal) to 4 hours postprandial at 5min intervals

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Glucose Excursion Time Frame: From baseline (start of meal) to 4 hours postprandial at 5min intervals	The excursion is calculated by subtracting the baseline glucose from each 5min CGM reading over 4 hours. For example if at baseline the glucose is 9mmol/l and at 5min postprandial it is 9.3mmol/l the excursion at 5min is 0.3mmol/l. The mean excursion is then calculated over 4 hours for each breakfast meal (381) which had a glucose reading at baseline.	From baseline (start of meal) to 4 hours postprandial at 5min intervals
Peak Glucose Excursion Time Frame: From baseline (start of meal) to 4 hours postprandial at 5 min intervals	The peak glucose excursions calculated from the CGM readings for 381 breakfast meals over 4 hour postprandial period - this is the highest excursion over the 4 hour period	From baseline (start of meal) to 4 hours postprandial at 5 min intervals
Time to Peak Time Frame: From baseline (start of meal) to 4 hours postprandial at 5 min intervals	From CGM data. This is the time of the highest excursion over the 4-hour period	From baseline (start of meal) to 4 hours postprandial at 5 min intervals
Area Under the Curve Time Frame: From baseline (start of meal) to 4 hours postprandial at 5 min intervals	Calculated from the CGM readings for 381 breakfast meals over 4 hour postprandial period	From baseline (start of meal) to 4 hours postprandial at 5 min intervals
Coefficient of Variation Percentage Time Frame: From baseline (start of meal) to 4 hours postprandial	Calculated from the CGM reading for 387 breakfast meals over 4 hour postprandial period	From baseline (start of meal) to 4 hours postprandial
Time in Range (Minutes) Time Frame: From baseline (start of meal) to 4 hours postprandial at 5min intervals	Calculated from the CGM readings for 387 breakfast meals over 4 hour postprandial period. Time in range refers to the time spent with a glucose reading between 3.9-10mmol/l	From baseline (start of meal) to 4 hours postprandial at 5min intervals
CV% and Glycaemic Index (GI) of Breakfast Meal Time Frame: From baseline (start of meal) to 4 hours postprandial	The CV% taken from CGM data over a 4hour postprandial period from the ingestion of breakfast meals that had a high and medium glycaemic index	From baseline (start of meal) to 4 hours postprandial
Mean Postprandial Glucose and Glycaemic Index of Breakfast Meal Time Frame: From baseline (start of meal) to 4 hours postprandial	Mean postprandial glucose from CGM data after ingestion of breakfast meal by three categories of glycaemic index (low medium and high)	From baseline (start of meal) to 4 hours postprandial
Mean Postprandial Glucose and Glycaemic Load of Breakfast Meals Time Frame: From baseline (start of meal) to 4 hours postprandial	Mean postprandial glucose from CGM data after ingestion of breakfast meals across three categories of glycaemic load (low, medium and high)	From baseline (start of meal) to 4 hours postprandial
Time to Peak Across Categories of Glycaemic Load Time Frame: From baseline (start of meal) to 4 hours postprandial	CGM data over 4 hour postprandial period for three categories of glycaemic load.	From baseline (start of meal) to 4 hours postprandial
Mean Postprandial Glucose and Type of Breakfast Meal Time Frame: From baseline (start of meal) to 4 hours postprandial	Mean postprandial glucose from CGM data over four hours postprandial period after ingestion of breakfast meal containing a ready to eat cereal compared with breakfast meals containing a protein food	From baseline (start of meal) to 4 hours postprandial
Coefficient of Variation Percentage Over 90 Days Time Frame: 90 days	This measures the amount of dispersion (spread) around the mean. It is calculated from the standard deviation divided by the mean and multiplied by 100 to give a percentage. This was taken from the standard deviation and mean from up to 90 days of retrospective CGM data (mean of 79.3 days of CGM readings). This represents how much glucose moves up and down. %CV of 36% or less indicates stable glucose	90 days
Diurnal Coefficient of Variation Percentage Over 90 Days Time Frame: 90 days of CGM data	This measures the amount of dispersion (spread) around the mean. It is calculated from the standard deviation divided by the mean and multiplied by 100 to give a percentage. This was taken from the standard deviation and mean from up to 90 days of retrospective CGM data (mean of 79.3 days of CGM readings) for the 06.00-22.00 period of time. This represents how much glucose moves up and down. A CV% of 36% or less indicates stable glucose	90 days of CGM data
Nocturnal Coefficient of Variation Percentage Over 90 Days Time Frame: 90 days of CGM data	This measures the amount of dispersion (spread) around the mean. It is calculated from the standard deviation divided by the mean and multiplied by 100 to give a percentage. This was taken from the standard deviation and mean from up to 90 days of retrospective CGM data (mean of 79.3 days of CGM readings) for the 22.00 - 06.00 period of time. This represents how much glucose moves up and down. A CV% of 36% or less indicates stable glucose	90 days of CGM data

Collaborators and Investigators

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

Sponsor

University of Stirling

Investigators

Principal Investigator: Julie Johnson, MNutr, University of Stirling

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

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 6, 2021

Primary Completion (Actual)

November 20, 2021

Study Completion (Actual)

November 20, 2021

Study Registration Dates

First Submitted

August 6, 2024

First Submitted That Met QC Criteria