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Trial registered on ANZCTR


Registration number
ACTRN12619001538134
Ethics application status
Approved
Date submitted
29/10/2019
Date registered
7/11/2019
Date last updated
29/06/2022
Date data sharing statement initially provided
7/11/2019
Date results information initially provided
29/06/2022
Type of registration
Prospectively registered

Titles & IDs
Public title
Reduced-Carbohydrate Diets for Type 1 Diabetes Management: A Retrospective Case Series
Scientific title
Clinical Application of Reduced-Carbohydrate Diets for Type 1 Diabetes Management: A Retrospective Case Series
Secondary ID [1] 299663 0
None
Universal Trial Number (UTN)
U1111-1242-7002
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
type 1 diabetes mellitus 315001 0
Condition category
Condition code
Metabolic and Endocrine 313337 313337 0 0
Diabetes

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
a) Carbohydrate-focused dietary interventions, including any intervention that prioritises the amount and/or type of dietary carbohydrate to be consumed amount, that are designed and delivered by a Credentialed Diabetes Educator and Accredited Practising Dietitian. It is expected that carbohydrate-focused dietary interventions will include low- (<26% total energy as carbohydrate), moderate- (26-45% total energy as carbohydrate) and high-carbohydrate (45-65% total energy as carbohydrate) diets.
b) Participant involvement is minimal, with a total of 20 minutes expected. Participants are required to provide informed consent to access medical records and will be asked to complete a short online questionnaire for collection of demographic characteristics and general health information. This includes age, sex, ethnicity, religion, education level, duration of diabetes, co-morbidities (i.e., other active diseases/conditions), and medication use. Participants may also be contacted via telephone for clarification of any information they provide.
c) The duration of observation per participant may be from 2 weeks up to 2 years. The minimum duration of exposure to the diet intervention for inclusion is 2 weeks, and we expect that participants will have been exposed to the diet for varying durations.
Intervention code [1] 315927 0
Not applicable
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 321818 0
Haemoglobin A1c (HbA1c). The assessment of this outcome may vary between participants. We will extract all HbA1c values and report how they were assessed as part of our results. We will include HbA1c values that were self-reported by participants, reported on a medical letter/doctor referral to the clinic, assessed using a finger-prick device and/or assessed via standard laboratory blood testing.
Timepoint [1] 321818 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all HbA1c values from participant records, and compare the HbA1c from baseline (pre value) with the HbA1c closest to the end of the participant's exposure to the diet (post value).
Primary outcome [2] 331838 0
Estimated A1c (eA1c). This outcome will be assessed via uploaded reports from continuous blood glucose monitoring devices or flash glucose monitoring devices.
Timepoint [2] 331838 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all eA1c data points from participant records, and compare the baseline value (pre value) with the value closest to the end of the participant's exposure to the diet (post value).
Secondary outcome [1] 376303 0
Glycaemic variability. This outcome will be assessed via uploaded daily reports from continuous blood glucose monitoring devices or flash glucose monitoring devices. If more than one day's worth of data is available, the average of up to 3 days closest to pre-post dates will be used.
Timepoint [1] 376303 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all glycaemic variability data from participant records, and compare the baseline value (pre value) with the value closest to the end of the participant's exposure to the diet (post value).
Secondary outcome [2] 376304 0
Fasting blood glucose. This outcome will be assessed using any finger-prick blood glucose monitoring device.
Timepoint [2] 376304 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all fasting blood glucose data from participant records, and compare the baseline value (pre value) with the value closest to the end of the participant's exposure to the diet (post value).
Secondary outcome [3] 376306 0
Total daily insulin dose. If uploaded data from an insulin pump is available, this will be used. Otherwise, this outcome will be assessed via self-report 1-day averages of total rapid acting insulin dosages + total long acting insulin dosages. In any case, if more than one day's worth of data is available, the average of up to 3 days closest to pre-post dates will be used.
Timepoint [3] 376306 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all total daily insulin dose data from participant records, and compare the baseline value (pre value) with the value closest to the end of the participant's exposure to the diet (post value).
Secondary outcome [4] 376307 0
Patient-reported well-being as assessed by methods of the CDE/APD (healthcare practitioner who delivered diet intervention to patient). Self-report participant data relating to diet satisfaction, quality of life, social/emotional well-being, etc. will be used verbatim.
Timepoint [4] 376307 0
Pre-post duration of exposure to the diet. As the duration of exposure will vary among participants, we will extract all patient-reported well-being data from participant records, and compare the baseline value (pre value) with the value closest to the end of the participant's exposure to the diet (post value).

Eligibility
Key inclusion criteria
To be included in the study, participants must be adults (18-60 years) with previously diagnosed type 1 diabetes (T1D), attended at least two consultations (greater than or equal to 2 weeks apart) with the research site’s (Type 1 Diabetes Family Centre in Perth, Western Australia) Credentialed Diabetes Educator & Accredited Practising Dietitian (CDE/APD) for dietary advice regarding a reduced-carbohydrate diet, and have the following data items available: sex, age, prescribed carbohydrate amount (as grams per day, %TEI or a clear description of the types of foods to include and avoid) and pre-post values for at least one primary or secondary clinical outcome. The primary outcome is HbA1c and estimated A1c (eA1c), and secondary outcomes are glycaemic variability, mean fasting blood glucose levels, total daily insulin use, and patient-reported well-being.
Minimum age
18 Years
Maximum age
60 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
There are no key exclusion criteria. Eligible participants must satisfy the key inclusion criteria only.

Study design
Purpose
Natural history
Duration
Longitudinal
Selection
Defined population
Timing
Both
Statistical methods / analysis
Recruitment
All existing patients of the centre will be invited to participate in the study. A flyer and participant information sheet will be emailed to potentially eligible participants by the centre’s administration team to inform them of the opportunity to participate in the research. The list of consenting participants will be provided to a designated staff member of the centre who has no existing dependent relationships with any potentially eligible participant, and this staff member will make a copy of all consenting patient records to be stored on a password-protected external hard drive for assessment by the primary investigator (JT). All patients that provide consent before the pre-specified cut-off date will have their clinical data assessed for eligibility by JT.

Data Collection
Participants will also be asked to complete a short questionnaire on REDCap at the time of consent to provide demographic data and general health information, including age, sex, ethnicity, religion, education level, BMI, diabetes duration, co-morbidities, and use of medications. If any of these data items are also recorded in the patient file, they will be extracted by JT and used to confirm the information provided by the participants in the questionnaires. Any discrepancies between the two modes of data will be resolved by calling the patient for clarification and verification, otherwise the data item(s) will be excluded. Data relating to the dietary intervention and clinical outcomes will be extracted by JT from a private room at the centre during which time JT will replace participant names and other personal identifiers with a research identification number. The following data will be extracted (verbatim) using a customised data extraction form in Microsoft Excel:
- Details on the prescribed dietary intervention
- Details on delivery techniques used
- Details on additional intervention components (e.g., insulin regimen, physical activity)
- Outcomes used to evaluate the dietary intervention (self-report or verified)
- Length of follow-up
- Pre-post outcome values
- Adherence to dietary prescription
- Adverse effects/experiences, if any

Data Synthesis & Analysis
All data will be entered in to a secure online database without identifiers and made available to all other investigators (KR, RJ, AR, GB, HP) for collaborative analysis.

Objective 1: Thematic analysis will be used to assess the dietary prescription details and identify the core components involved in the formulation of carbohydrate-focused diet intervention(s) for T1D management. All investigators (JT, KR, GB, RJ, AR, HP) will collaboratively compare and contrast the initial themes identified in the data until consensus is reached on a final set of core dietary components.

Objective 2: Descriptive statistics for calculation will include means and standard deviations of continuous variables and proportions for categorical variables. The analysis used will be a paired t-test comparing changes in HbA1c, glycaemic variability, mean fasting blood glucose levels, and total daily insulin use from baseline to follow-up. Any reported pre-post change(s) in patient well-being will be presented verbatim in text and/or tabular format. Individual participant results will also be presented in tabular format (case-by-case).

Objective 3: Participants will be classified into one of four groups:
1. Very low-carbohydrate ketogenic diet (<50 g/day)
2. Low-carbohydrate diet (50-130 g/day)
3. Moderate carbohydrate diet (130-225 g/day)
4. High carbohydrate diet (>225 g/day)
The mean (pre-post) change for each outcome will be calculated and compared between groups using correlational analysis. We plan to use a one-way ANCOVA for the change in each outcome variable (HbA1c, glycaemic variability, mean fasting blood glucose levels, and total daily insulin use), with the four carbohydrate groups as fixed factors and age, sex, and BMI as covariates. If adequate quantitative data on the dietary carbohydrate prescriptions are available, we will use a dose-response regression analyses between continuous carbohydrate (g/day) and outcome variables, adjusting for potential confounders (i.e., age, sex, BMI) as covariates.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
11/11/2019
Actual
12/11/2019
Date of last participant enrolment
Anticipated
20/12/2019
Actual
12/12/2019
Date of last data collection
Anticipated
31/01/2020
Actual
15/01/2020
Sample size
Target
20
Accrual to date
Final
26
Recruitment in Australia
Recruitment state(s)
WA
Recruitment postcode(s) [1] 28354 0
6021 - Stirling

Funding & Sponsors
Funding source category [1] 304136 0
Self funded/Unfunded
Name [1] 304136 0
Country [1] 304136 0
Primary sponsor type
Individual
Name
Jessica Turton
Address
The University of Sydney, Camperdown NSW 2006.
Country
Australia
Secondary sponsor category [1] 304368 0
Individual
Name [1] 304368 0
Kieron Rooney
Address [1] 304368 0
The University of Sydney, Camperdown NSW 2006.
Country [1] 304368 0
Australia
Other collaborator category [1] 281006 0
Individual
Name [1] 281006 0
Grant Brinkworth
Address [1] 281006 0
CSIRO, Building 53/11 Julius Ave, North Ryde NSW 2113.
Country [1] 281006 0
Australia
Other collaborator category [2] 281007 0
Individual
Name [2] 281007 0
Helen Parker
Address [2] 281007 0
The University of Sydney, Camperdown NSW 2006.
Country [2] 281007 0
Australia
Other collaborator category [3] 281008 0
Individual
Name [3] 281008 0
Rebecca Johnson
Address [3] 281008 0
Type 1 Diabetes Family Centre, 11 Limosa Close, Stirling Western Australia 6021.
Country [3] 281008 0
Australia
Other collaborator category [4] 281009 0
Individual
Name [4] 281009 0
Amy Rush
Address [4] 281009 0
Type 1 Diabetes Family Centre, 11 Limosa Close, Stirling Western Australia 6021.
Country [4] 281009 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 304619 0
The University of Sydney Human Research Ethics Committee
Ethics committee address [1] 304619 0
Research Integrity & Ethics Administration
Research Portfolio
Level 3, F23 Administration Building
The University of Sydney
NSW 2006 Australia
Ethics committee country [1] 304619 0
Australia
Date submitted for ethics approval [1] 304619 0
Approval date [1] 304619 0
23/09/2019
Ethics approval number [1] 304619 0
Project number: 2019/668

Summary
Brief summary
Diet remains a cornerstone of type 1 diabetes (T1D) management, with carbohydrate intake having the greatest impact on insulin requirements and blood glucose fluctuations. However, there is limited scientific evidence comparing the effect(s) of different levels of carbohydrate intake on T1D management. A T1D outpatient centre in Perth WA has been actively implementing carbohydrate-focused diet interventions, including low-carbohydrate diets, for T1D. This presents an opportunity to conduct a chart review to better understand the effect(s) of varying levels of carbohydrate on T1D management outcomes, and to identify and describe effective dietary approaches for this clinical population. We expect that low-carbohydrate diets (<130 g/day) will lead to improvements in T1D management due to reduced error rates in calculating exogenous insulin requirements.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 97610 0
Ms Jessica Turton
Address 97610 0
The University of Sydney, Camperdown NSW 2006.
Country 97610 0
Australia
Phone 97610 0
+612 9137 5649
Fax 97610 0
Email 97610 0
[email protected]
Contact person for public queries
Name 97611 0
Jessica Turton
Address 97611 0
The University of Sydney, Camperdown NSW 2006.
Country 97611 0
Australia
Phone 97611 0
+612 9137 5649
Fax 97611 0
Email 97611 0
[email protected]
Contact person for scientific queries
Name 97612 0
Jessica Turton
Address 97612 0
The University of Sydney, Camperdown NSW 2006.
Country 97612 0
Australia
Phone 97612 0
+612 9137 5649
Fax 97612 0
Email 97612 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
All extracted de-indentified data will be presented as means (and variances) and as individual data as part of the scientific report, so there will be no additional data to share. However, should there be any additional information that is not reported publicly, this will be available on request so long as participant data is not re-identifiable.
When will data be available (start and end dates)?
The data will be available for 5 years from the date it is collected (December 2019).
Available to whom?
Those who request it.
Available for what types of analyses?
Any.
How or where can data be obtained?
By emailing the principal investigator, [email protected].


What supporting documents are/will be available?




Results publications and other study-related documents

Documents added manually
TypeIs Peer Reviewed?DOICitations or Other DetailsAttachment
Study results articleYes Turton J, Brinkworth G, Parker H, Rush A, Johnson ... [More Details]

Documents added automatically
No additional documents have been identified.