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Trial registered on ANZCTR


Registration number
ACTRN12621000081819
Ethics application status
Approved
Date submitted
1/12/2020
Date registered
1/02/2021
Date last updated
1/02/2021
Date data sharing statement initially provided
1/02/2021
Type of registration
Retrospectively registered

Titles & IDs
Public title
Does High vs Low Glycemic Index Impact the Postprandial Glycaemic Response to Meals High in Protein and Fat in Adults with Type 1 Diabetes?
Scientific title
In the context of a high protein, high fat meal, does a high glycemic index carbohydrate compared to a low glycemic index carbohydrate impact the postprandial glycaemic response in adults with type 1 diabetes?
Secondary ID [1] 302886 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 1 Diabetes 319889 0
Condition category
Condition code
Metabolic and Endocrine 317822 317822 0 0
Diabetes

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
To determine the impact of a high glycaemic index (GI) carbohydrate vs a low GI carbohydrate in a meal high in carbohydrate, fat & protein on postprandial glycaemia in adults with type 1 diabetes.
A randomised, within-subject trial comparing capillary postprandial glycaemia for a high GI white bread vs a low GI white bread served with 55g of peanut butter over 5h with the same insulin dose for all meals (based on the insulin: CHO ratio) in 12 adults with T1D using insulin pump therapy or multiple daily injections.

Design Rationale
For individuals with type 1 diabetes, currently the amount of carbohydrate in meals is the predominant factor that determines their meal time insulin dosage. However, recent research has shown that the amount of fat, protein and GI of meals can also impact the postprandial glycaemic response. This study will establish the relationship between GI and glycaemia for meals also high in protein and fat. Fat and protein will be added in the form of peanut butter.

Test Meals & Insulin Doses
Insulin doses calculated using participants’ insulin: CHO ratio (standard clinical practice).

Test Meal 1: 2 slices of high GI toast (GI: 70) with 55g of peanut butter (35g CHO, 30g protein, 18g fat)
Test Meal 2: 2 slices of low GI toast (GI: 52) with 55g of peanut butter (35g CHO, 30g protein, 18g fat)

Wash out period: All test sessions must be completed on separate days but may be consecutive days.

Study Procedure:
Participants will be instructed to avoid alcohol and exercise for 24h prior to the session and not make any manual insulin adjustments (correction bolus or temporary basal rate) after midnight. Participants will be instructed to fast from midnight, with only water allowed. In the case of hypoglycaemia, participants will be instructed to treat their hypoglycaemia according to their usual clinical care and their test session will be rescheduled.
Participants will be asked to attend the Clinical Research Facility for a screening appointment (approximately 30 minutes), to confirm eligibility, complete informed consent, provide instruction on the trial, provide test meals and commence the continuous glucose monitoring system (Abbott Freestyle Libre). Participants will be asked to complete the two test sessions at home within the next 14 days. The researchers will provide support and training through telephone or video conference. To ensure adherence to study protocol, participants' overnight and preprandial blood glucose level will be checked by researchers using CGM cloud data before the commencement of the test sessions. Also a case report form will be given to participants to ensure they fulfill all requirement (fasting and avoid exercises) the night before and during the test sessions. Test meals are weighted and supplied by research team.
On the day of the test session, participants will be asked to start the session between 7:00-9:00am after an overnight fast. The fasting capillary blood glucose test must be between 4-10 mmol/L for the session to be commenced. The allocated insulin dose will be self-administered via insulin infusion through insulin pump into abdomen or subcutaneous injection into abdomen for people doing multiple daily injections. 15 minutes immediately prior to the consumption of the test meal. The test food will be served with 250mL of plain water and participants will be given 12 minutes to consume both the food and water and then no other food or drink allowed for the remainder of the 5h test session (except water). The CGM system will record the interstitial blood glucose level every 5 minutes throughout the test session. If hypoglycaemia occurs (> 3.5 mmol/L), the test session will be terminated, the event recorded and the participant treated appropriately.
Intervention code [1] 319171 0
Treatment: Other
Comparator / control treatment
This is a within subject trial and thus subjects serve as their own control. Blood glucose levels and insulin doses for different test meals will be compared within each individual.
Control group
Active

Outcomes
Primary outcome [1] 325845 0
Differences in 3hr iAUCglucose
Timepoint [1] 325845 0
The 3hr iAUCglucose will be calculated from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 3 hrs (0-180 minutes inclusive).
Secondary outcome [1] 389328 0
Incidence of hypoglycaemia (< 3.5mmol/L)
Timepoint [1] 389328 0
The incidence of hypoglycaemia will be recorded from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [2] 389333 0
Mean postprandial blood glucose level
Timepoint [2] 389333 0
The mean postprandial blood glucose level will be calculated from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [3] 389334 0
Standard deviation around mean postprandial blood glucose level
Timepoint [3] 389334 0
The standard deviation around mean postprandial blood glucose level will be calculated from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [4] 389335 0
Coefficient of Variation in blood glucose levels
Timepoint [4] 389335 0
The Coefficient of Variation will be calculated from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [5] 389336 0
J-Index of blood glucose levels
Timepoint [5] 389336 0
The J-Index will be calculated from capillary blood glucose level measurements taken at at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [6] 389337 0
Mean Amplitude of Glycaemic Excursion (MAGE)
Timepoint [6] 389337 0
The Mean Amplitude of Glycaemic Excursion (MAGE) will be calculated from capillary blood glucose level measurements taken at at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).
Secondary outcome [7] 389338 0
5hr iAUCglucose
Timepoint [7] 389338 0
The 5hr iAUCglucose will be calculated from capillary blood glucose level measurements taken at 5 minute intervals by CGM for 5 hrs (0-300 minutes inclusive).

Eligibility
Key inclusion criteria
Aged 18-70 years, T1D diagnosed for greater than or equal to 1 year, HbA1c less than or equal to 8.5% (69 mmol/mol), using insulin pump therapy or multiple daily injections (MDI), reliably performing self-monitoring of blood glucose at least four times daily and fluency in English.
Minimum age
18 Years
Maximum age
70 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Concurrent medical issues including coeliac disease and gastroparesis, food allergies, intolerances or eating disorders or use of other medication that may influence blood glucose levels, pregnancy or lactation.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The order of the 2 meals will be randomised but the randomisation sequence and allocation will not be concealed. The randomisation sequence will be generated using a computerised sequence generator.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
10 subjects will provide 80% power to detect a difference in 3hr iAUCglucose of 100 mmol.min/L, allowing for a standard deviation (SD) of 75 mmol.min/L. To allow for a 20% margin for dropouts, a total of 12 subjects will be recruited.
If the session is stopped due to hypoglycaemia, the last recorded value will be carried forward. A general linear model with preprandial blood glucose level as a covariate will be used to analyse the parameters for the test conditions. The number of episodes of hypoglycaemia will be expressed as a proportion of all test sessions and compared by Chi-Square test and a Kaplan-Meier survival plot. Differences in coefficients will be considered statistically significant if p is < 0.05, and highly significant if p is < 0.01 (two-tailed).

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
15/01/2021
Date of last participant enrolment
Anticipated
8/02/2021
Actual
Date of last data collection
Anticipated
16/02/2021
Actual
Sample size
Target
12
Accrual to date
9
Final
Recruitment in Australia
Recruitment state(s)
NSW
Recruitment hospital [1] 18115 0
Royal Prince Alfred Hospital - Camperdown
Recruitment postcode(s) [1] 32108 0
2050 - Camperdown

Funding & Sponsors
Funding source category [1] 307306 0
University
Name [1] 307306 0
University of Sydney
Country [1] 307306 0
Australia
Primary sponsor type
University
Name
University of Sydney
Address
Charles Perkins Centre
University of Sydney
John Hopkins Dr
University of Sydney NSW 2006
Country
Australia
Secondary sponsor category [1] 307944 0
None
Name [1] 307944 0
Address [1] 307944 0
Country [1] 307944 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 307401 0
Sydney Local Health District Ethics Review Committee (RPAH Zone) [EC00113]
Ethics committee address [1] 307401 0
Research Ethics and Governance Office
Royal Prince Alfred Hospital
Missenden Rd
Camperdown NSW 2050
Ethics committee country [1] 307401 0
Australia
Date submitted for ethics approval [1] 307401 0
13/11/2020
Approval date [1] 307401 0
23/12/2020
Ethics approval number [1] 307401 0
X17-0056

Summary
Brief summary
Do you have type 1 diabetes and want to know how the glycemic index affects your blood glucose levels?
The ‘iBolus: GI’ Study is exploring at how the glycemic index in meals high in protein and fat influences blood glucose levels in adults with type 1 diabetes and using insulin pump or multiple daily injections. You will be asked to have a blood test and do the test sessions at home with remote training and support by researchers to eat two different type of toast (high and low GI) served with peanut butter, take an insulin bolus and monitor your BGL by CGM system for 5.5 hr.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 107102 0
Dr Kirstine Bell
Address 107102 0
Charles Perkins Centre
The University of Sydney NSW 2006
Country 107102 0
Australia
Phone 107102 0
+61 2 8627 4250
Fax 107102 0
Email 107102 0
[email protected]
Contact person for public queries
Name 107103 0
Kirstine Bell
Address 107103 0
Charles Perkins Centre
The University of Sydney NSW 2006
Country 107103 0
Australia
Phone 107103 0
+61 2 8627 4250
Fax 107103 0
Email 107103 0
[email protected]
Contact person for scientific queries
Name 107104 0
Kirstine Bell
Address 107104 0
Charles Perkins Centre
The University of Sydney NSW 2006
Country 107104 0
Australia
Phone 107104 0
+61 2 8627 4250
Fax 107104 0
Email 107104 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Individual participant data will not be made available as consent has not been obtained for this


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
9911Study protocol  [email protected]
9912Informed consent form  [email protected]
9913Ethical approval  [email protected]



Results publications and other study-related documents

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