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Trial registered on ANZCTR


Registration number
ACTRN12621000764831
Ethics application status
Approved
Date submitted
18/05/2021
Date registered
21/06/2021
Date last updated
21/06/2021
Date data sharing statement initially provided
21/06/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
A Novel Dietary Approach in Adults with Type 1 Diabetes
Scientific title
Effects of a Low-Carbohydrate Diet on HbA1c levels in Adults with Type 1 Diabetes: An Interventional Study
Secondary ID [1] 304251 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
type 1 diabetes 321960 0
Condition category
Condition code
Metabolic and Endocrine 319683 319683 0 0
Diabetes

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a 28-week single arm within-participant intervention study involving a 4-week control period, a 12-week intervention period and a 12-week follow-up.

This study will investigate a 12-week low-carbohydrate (LC) diet with an adaptive carbohydrate prescription. The prescription will start at 50 g of digestible carbohydrate per day for the first 4 weeks, then it can be adapted (increased or decreased) within a broader range of 25-75 g/day according to individual blood glucose levels and personal preference. Participants will meet individually with the study dietitian for a total of six 1-hour fortnightly sessions to receive dietary instruction, strategies and education. The first and last diet session will be delivered in-person, while the other diet sessions will be delivered via Telehealth (video conference). Participants will be required to test their blood glucose levels at least six times daily, in accordance with standard diabetes management practices, using whatever method(s) they usually use to test glucose. The dietitian will review participants' dietary intake (via diet history or Easy Diet Diary mobile App tracking) and blood glucose levels to monitor adherence to the intervention throughout the study.

The purpose of this study is to investigate a LC dietary intervention. However, it is not possible to make major changes to the dietary management of T1D without considering the subsequent required change(s) to insulin management. As such, all participants will be supported by a member of their usual diabetes care team and provided with an information pack (developed by the study diabetes educator, dietitian, physician and endocrinologist) at the beginning of the study that contains suggested guidelines for insulin management on a LC diet. The information pack includes resources relating to general considerations for insulin management on a LC diet; blood glucose self-monitoring; managing hypoglycaemia; and managing sick days.

For safety purposes, participants will be required to self-monitor either urine or blood ketones regularly throughout the intervention period using their usual method(s) of measuring ketones. Participants will be required to measure their ketones at least twice per week, and more under certain circumstances (e.g., if feeling unwell) as per standard of care diabetes practices.

Prior to starting the dietary intervention, participants will undertake a 4-week control period where they will be asked to maintain their usual dietary intakes and diabetes management practices. They will be provided with basic diet- and diabetes-related education by the dietitian, including information on carbohydrate counting, food label reading, blood glucose monitoring and managing hypoglycaemia. Once participants have completed the 4-week control period, they will start the intervention period immediately.
Intervention code [1] 320586 0
Lifestyle
Intervention code [2] 320815 0
Treatment: Other
Comparator / control treatment
Habitual diets higher in carbohydrates (>150 g/day).

During the 4-week control period, participants will be provided with instructions to maintain usual patterns of eating, exercise and diabetes management. However, participants will be required to test their blood glucose levels at least six times daily, in accordance with standard diabetes management practices, using whatever method(s) they usually use to test glucose. The dietitian will provide some basic diabetes-related education and written resources, and there there will be a diet session scheduled in after 2 weeks to provide some information on carbohydrate counting and reading food labels during the control period. The education and contact frequency of the control period is designed to be relative to that of the intervention period.
Control group
Active

Outcomes
Primary outcome [1] 327564 0
Haemoglobin A1c, HbA1c (% and mmol/mol) [biological samples will be collected and analysed by a NATA-Accredited Laboratory (Australian Clinical Labs) using standard procedures]
Timepoint [1] 327564 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment), (4) follow-up (Week 28 post-enrolment)
Secondary outcome [1] 395675 0
Glycaemic variability marker (Standard Deviation (SD) intraday) [derived from 7-day continuous blood glucose monitoring (CGM) data using devices supplied by Medtronic Australasia]
Timepoint [1] 395675 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [2] 395676 0
Frequency of hypoglycaemia (<3.5 mmol/L with or without symptoms) [derived from 7-day CGM data]
Timepoint [2] 395676 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [3] 395677 0
Total daily insulin (TDI) [the sum of all long-acting and rapid-acting insulin given over a 24-hour period derived from a 3-day self-report insulin log]
Timepoint [3] 395677 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [4] 395678 0
Quality of life [measured using the 15-item DQOL Brief Clinical Inventory]
Timepoint [4] 395678 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [5] 396751 0
Mean amplitude of glycaemic excursions (MAGE) [derived from 7-day continuous blood glucose monitoring (CGM) data using devices supplied by Medtronic Australasia]
Timepoint [5] 396751 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [6] 396967 0
Body Mass Index (BMI) (kg/m2) [height and weight measured using standard procedures by study dietitian]
Timepoint [6] 396967 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [7] 396968 0
Waist circumference (cm) [measured at the midline point between the lowest rib and iliac crest by study dietitian]
Timepoint [7] 396968 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [8] 396969 0
Resting blood pressure (BP) (mmHg) [measured after 5 minutes of seated rest using an automated BP machine by study dietitian]
Timepoint [8] 396969 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [9] 396970 0
Fasting blood glucose (mmol/L) [biological samples collected and analysed by a NATA-Accredited Laboratory (Australian Clinical Labs) using standard procedures]
Timepoint [9] 396970 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [10] 396971 0
Kidney function [biological samples collected and analysed by a NATA-Accredited Laboratory
(Australian Clinical Labs) using standard procedures]
Timepoint [10] 396971 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [11] 396972 0
Liver function [biological samples collected and analysed by a NATA-Accredited Laboratory
(Australian Clinical Labs) using standard procedures]
Timepoint [11] 396972 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [12] 396973 0
Lipid studies [biological samples collected and analysed by a NATA-Accredited Laboratory
(Australian Clinical Labs) using standard procedures]
Timepoint [12] 396973 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [13] 396974 0
Physical activity level [self-report using the International Physical Activity Questionnaire]
Timepoint [13] 396974 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [14] 396975 0
Dietary intake [derived from self-report 3-day weighed food record collected using Xyris Easy Diet Diary and analysed using Xyris FoodWorks Professional Edition]
Timepoint [14] 396975 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)
Secondary outcome [15] 396976 0
Diet satisfaction [self-report using a 6-item questionnaire]
Timepoint [15] 396976 0
(1) Pre-control period (Week 0), (2) post-control period/pre-intervention period (Week 4 post-enrolment), (3) post-intervention period (Week 16 post-enrolment)

Eligibility
Key inclusion criteria
• Adults aged 18-60 yrs
• Residing within Australia
• Previously diagnosed T1D (confirmed with specialist letter/correspondence, diabetes duration greater than or equal to 6 months, using multiple daily injections of insulin and/or insulin pump)
• Suboptimal glycaemic control (HbA1c greater than 7.0%)
• BMI 18.5-39.9 kg/m2
• Habitual dietary intake contains more than 150 g/day of total carbohydrates (assessed by a 24-hour diet recall collected by study dietitian)
• Independent free-living, able to understand study requirements, speak and understand fluent English, and both physically and cognitively able to provide their informed consent
• Willing and able to self-monitor blood glucose levels using both finger-prick and/or continuous blood glucose monitoring devices on a daily basis
• Willing and able to learn and utilise dietary carbohydrate and protein counting skills
• Willing and able to titrate insulin dosages according to their dietary carbohydrate (and/or protein) intake in consultation with a member of their usual diabetes care team
• Owns and can competently use an iOS or Android mobile device that is able to receive text messages/calls and download free mobile applications from the App Store or Google Play
• Has access to and can competently use a computer, mobile or tablet device with internet connection for uploading data onto REDCap and for Zoom conferencing
• Be willing and able to attend the clinic rooms at the Susan Wakil Building (The University of Sydney, Camperdown NSW 2006) to meet with the study dietitian on six separate occasions throughout the study
• Be willing to visit an Australian Clinical Labs collection centre (https://www.clinicallabs.com.au/location/) on four separate occasions throughout the study
Minimum age
18 Years
Maximum age
60 Years
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
• HbA1c equal to or less than 7.0%
• Underweight (BMI less than 18.5 kg/m2) or class III obesity (BMI greater than or equal to 40 kg/m2)
• Habitual use of an automated insulin delivery system to control blood glucose levels
• Habitual adherence to a fixed insulin regimen such that they are not confident in titrating insulin dosages according to their dietary intake.
• Previously diagnosed hypo unawareness
• Non-English speaking or unable to understand English
• Previous medical diagnosis of cognitive impairment and/or mental illness (not including depression and anxiety)
• Using medication to manage depression and/or anxiety and medications have been increased within the last three months
• Current physical impairment or disability that limits individual capacity to communicate with researchers and/or use the mobile application Easy Diet Diary (e.g., blind/vision impaired/deaf/speech impaired)
• Habitual dietary intake contains equal to or less than 150 g/day of total carbohydrates
• Usual dietary intake strictly excludes animal-based protein (e.g., vegan diet)
• Undertaken major change(s) to their insulin delivery method and/or glucose monitoring method within the last three months, of which they are unfamiliar (e.g., switched from injections to insulin pump and has never used pump before, or from multiple daily finger pricks to CGM and has never used CGM before)
• Recent pregnancy or lactation (within the last six months)
• Planning to get pregnant within the next 12 months
• Self-identifies as current or recent smoker (within the last 6 months)
• Significant weight change (+/- 10% body weight) within the last three months
• Previous weight loss surgery
• History of malignancy (other than non-melanoma)
• History of thalassemia or other haemoglobinopathy
• Pre-existing anaemia
• Recent blood transfusion (within the last three months)
• A known family history of premature heart disease, including having a first-degree male relative (i.e., father or brother) or a first degree female relative (i.e., mother or sister) who had a heart attack, stroke or was diagnosed with cardiovascular disease before the ages of 55 or 65, respectively
• Previously diagnosed familial hypercholesterolaemia
• Previously diagnosed gastrointestinal disease (including inflammatory bowel disease [IBD]; not including irritable bowel syndrome [IBS] or coeliac disease), liver disease (including liver cirrhosis; not including fatty liver), chronic kidney disease (CKD; eGFR less than 60), respiratory disease (not including stable treated asthma), thyroid disease (including goitre; not including stable treated hyper- or hypothyroidism) or cardiovascular disease (including coronary heart disease, heart failure, cardiomyopathy, congenital heart disease, peripheral vascular disease and stroke; not including hyperlipidaemia or hypertension)
• Previously diagnosed neurological disorder (including high-frequency episodic migraine [10-14 headache days per month], chronic migraine [greater than or equal to 15 headache days per month], epilepsy, dementia, multiple sclerosis and Parkinson’s disease; not including low frequency migraines [less than 10 headache days per month])
• Previously diagnosed with a clinical eating disorder (including anorexia nervosa, bulimia nervosa or binge eating disorder) (within the last five years)
• Existing patient of Mrs Amy Rush (Credentialled Diabetes Educator), Dr David Lim (Medical Doctor), Dr Kevin Lee (Endocrinologist) or Ms Jessica Turton (Accredited Practising Dietitian)

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
N/A
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
N/A
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Single group
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Data will be analysed using the most up-to-date version of SPSS. Outcome results will be presented as means and standard deviations. One-Way Analysis of Variance (ANOVA) will be used to assess the within group differences across time for each outcome.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 308625 0
Other Collaborative groups
Name [1] 308625 0
CSIRO
Address [1] 308625 0
CSIRO
Bradfield Road
West Lindfield NSW 2070
Country [1] 308625 0
Australia
Primary sponsor type
University
Name
The University of Sydney
Address
The University of Sydney
Camperdown NSW 2006

Country
Australia
Secondary sponsor category [1] 309495 0
None
Name [1] 309495 0
None
Address [1] 309495 0
None
Country [1] 309495 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 308556 0
The University of Sydney Human Research Ethics Committee
Ethics committee address [1] 308556 0
The University of Sydney
Camperdown NSW 2006
Ethics committee country [1] 308556 0
Australia
Date submitted for ethics approval [1] 308556 0
30/04/2021
Approval date [1] 308556 0
01/06/2021
Ethics approval number [1] 308556 0
2021/080

Summary
Brief summary
Preliminary evidence suggests that low-carbohydrate (LC) diets appear safe for use in type 1 diabetes (T1D) and may be effective for certain subgroups of this clinical population. However, the available body of research is limited and there is still a lack of consensus regarding the efficacy of LC diets for improving T1D management. Since there are a multiplicity of lifestyle factors impacting T1D management, and with consideration that all individuals have their own personal needs and preferences, an interventional study that uses participants as their own controls and investigates a patient-led dietary approach will be of important clinical relevance. Therefore, a within-patient interventional study investigating a LC diet with an adaptive carbohydrate prescription (25-75 g/day) will be undertaken in adults with T1D in an outpatient setting. The aim of this research is to assess the efficacy of a LC diet in adults with T1D. Our primary objective is to determine the effects of a LC diet (25-75 g/day) on clinical markers of T1D management including HbA1c, glycaemic variability, frequency of hypoglycaemia, total daily insulin, and quality of life. We expect that a LC diet will result in improved T1D management compared to habitual diets higher in carbohydrates.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 111126 0
A/Prof Kieron Rooney
Address 111126 0
Susan Wakil Health Building
The University of Sydney
Camperdown NSW 2006
Country 111126 0
Australia
Phone 111126 0
+61 286271877
Fax 111126 0
Email 111126 0
kieron.rooney@sydney.edu.au
Contact person for public queries
Name 111127 0
Ms Jessica Turton
Address 111127 0
Susan Wakil Health Building
The University of Sydney
Camperdown NSW 2006
Country 111127 0
Australia
Phone 111127 0
+61 291375649
Fax 111127 0
Email 111127 0
Jessica.turton@sydney.edu.au
Contact person for scientific queries
Name 111128 0
Ms Jessica Turton
Address 111128 0
Susan Wakil Health Building
The University of Sydney
Camperdown NSW 2006
Country 111128 0
Australia
Phone 111128 0
+61 291375649
Fax 111128 0
Email 111128 0
Jessica.turton@sydney.edu.au

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 of the individual participant data collected during the trial, after de-identification.
When will data be available (start and end dates)?
From after the study has finished (~May 2022) until indefinitely.
Available to whom?
Anyone who wishes to access it.
Available for what types of analyses?
Any purpose.
How or where can data be obtained?
A copy of the study folder (de-identified data only) will be made and stored on an open access data sharing platform such as the Open Science Framework (OSF) (https://osf.io/).
What supporting documents are/will be available?
Study protocol
How or where can supporting documents be obtained?
Type [1] 11697 0
Study protocol
Citation [1] 11697 0
Link [1] 11697 0
Email [1] 11697 0
Other [1] 11697 0
We have submitted the study protocol to a scientific journal and it is currently under peer review. We will update this form with the relevant citation when it is available.
Attachment [1] 11697 0
Summary results
No Results