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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Different Diets in Gestational Diabetes
Scientific title
Investigating outcomes of reduced carbohydrate diets in Gestational Diabetes
Secondary ID [1] 299406 0
no secondary ID
Universal Trial Number (UTN)
Trial acronym
no trial acronym
Linked study record
No linked study

Health condition
Health condition(s) or problem(s) studied:
Gestational Diabetes 314581 0
Condition category
Condition code
Reproductive Health and Childbirth 312923 312923 0 0
Antenatal care
Metabolic and Endocrine 313059 313059 0 0

Study type
Description of intervention(s) / exposure
Individual, face to face dietary information session, advising the participant to aim for a daily carbohydrate intake of 120g. The advice provided is by a qualified dietician at the 'Diabetes in Pregnancy Clinic'. Dietician session usually lasts about 30 -60 minutes.
Intervention code [1] 315656 0
Comparator / control treatment
Individual, face to face dietary information session, advising the participant to aim for a daily carbohydrate intake of 215g. Advice provided by a qualified dietician at the 'Diabetes in Pregnancy Clinic'. Dietician session usually lasts about 30 -60 minutes.
Control group

Primary outcome [1] 321522 0
Weight gain per week as measured at the 'Diabetes in Pregnancy' clinic visits and recorded in the participant's hospital notes.

Timepoint [1] 321522 0
The initial primary outcome timepoint is when the participant first attends the 'Diabetes in Pregnancy' clinic.

Weight is measured at Diabetes in Pregnancy clinics held every Wednesday, women attend at regular intervals, increasing in frequency to once a week towards the end of their pregnancy.

The final primary outcome timepoint is the last 'Diabetes in Pregnancy 'clinic attended prior to the birth of her baby.
Secondary outcome [1] 375218 0
Average carbohydrate intake per day as measured by a food diary/ 24 hour food recall collected weekly throughout the pregnancy.

Timepoint [1] 375218 0
Food diary/recall collected each week from randomisation till the birth of the baby.
Secondary outcome [2] 375291 0
The proportion of time spent outside the target blood glucose levels on Continuous Glucose Monitoring (CGM). Target range is 4.0 mmol/L to 6.7 mmol /L CGM will occur for 14 days
Timepoint [2] 375291 0
CGM for 14 days commenced at the second visit to the Diabetes in Pregnancy Clinic. This visit is when randomisation to the intervention occurs.
CGM for 14 days measured again starting at 36 weeks gestation.

Key inclusion criteria
Women may be included if they have been diagnosed with gestational diabetes mellitus and present to the Wellington or Keneperu 'Diabetes in Pregnancy' clinics
Minimum age
18 Years
Maximum age
60 Years
Can healthy volunteers participate?
Key exclusion criteria
• First presentation to clinic >31 weeks gestation (Note must be randomised by 32 weeks)
• Type 1 diabetes mellitus
• Known pre-existing type 2 diabetes mellitus
• HbA1c at initial booking greater than or equal to 50mmol/mol
• Needs an interpreter into English for phone call with the research team

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation concealment achieved by computer randomisation package.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
This is a feasability study. We plan to include 20 women who present to the DIP clinic with GDM. This gives about 19 degrees of freedom with which to estimate a 95% CI for the standard deviation of the weight gain per week which gives good precision for this estimation. A lower confidence limit of SD of above 1.0 means that the planned RCT (requiring about 500 participant) could be done in a single centre; and of 1.25 would require two centres. We think the SD of this outcome will be different in the setting of an RCT because in the audit women presented to the clinic at any time between 5 and 39 weeks gestation with variable number of weight measurements. We will recruit women who are at most 32 weeks pregnant so that we will obtain at least six weeks of the intervention and at least two weight measurements whilst on the intervention. In this way the intervention will be as standardised as possible within a clinic environment and with a lesser degree of variability. The analysis of this primary outcome variable will use a Chi-square statistic to estimate the 95% CI for the standard deviation of this variable. Other data analyses, particularly for proportions, will be done however with the modest sample size confidence intervals for proportions will be very wide. The estimation of the difference in reported CHO intake will be by a t-test. Should the lower confidence limit for the estimate of difference in CHO level be less than 50g this will require substantial modification of our intervention to achieve a reasonable separation in CHO intake.

Recruitment status
Active, not recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 21886 0
New Zealand
State/province [1] 21886 0

Funding & Sponsors
Funding source category [1] 303912 0
Name [1] 303912 0
University of Otago
Address [1] 303912 0
University of Otago, Wellington,
23 Mein St
New Zealand
Country [1] 303912 0
New Zealand
Primary sponsor type
Rosemary Hall
Rosemary Hall,
University of Otago, Wellington
23 Mein St,
New Zealand
New Zealand
Secondary sponsor category [1] 304095 0
Name [1] 304095 0
Address [1] 304095 0
Country [1] 304095 0

Ethics approval
Ethics application status
Ethics committee name [1] 304416 0
Northern B Health and Disability Ethics Committee
Ethics committee address [1] 304416 0
Health and Disability Ethics Committees
Ministry of Health
133 Molesworth Street
PO Box 5013
Ethics committee country [1] 304416 0
New Zealand
Date submitted for ethics approval [1] 304416 0
Approval date [1] 304416 0
Ethics approval number [1] 304416 0

Brief summary
This is a feasibility study to investigate whether women with gestational diabetes who are attending a Diabetes in Pregnancy Clinic, are able to follow dietary intervention advice to reduce their carbohydrate intake. The study will assess weight gain during pregnancy, the effect on glucose control, insulin use and pregnancy and neonatal complications.
Trial website
Trial related presentations / publications
None to date
Public notes
None to date

Principal investigator
Name 96878 0
Dr Rosemary Hall
Address 96878 0
University of Otago, Wellington
23 Mein St
Country 96878 0
New Zealand
Phone 96878 0
+64 21863370
Fax 96878 0
Email 96878 0
Contact person for public queries
Name 96879 0
Dr Rosemary Hall
Address 96879 0
University of Otago, Wellington
23 Mein St
Country 96879 0
New Zealand
Phone 96879 0
+64 21863370
Fax 96879 0
Email 96879 0
Contact person for scientific queries
Name 96880 0
Dr Rosemary Hall
Address 96880 0
University of Otago, Wellington
23 Mein St
Country 96880 0
New Zealand
Phone 96880 0
+64 21863370
Fax 96880 0
Email 96880 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Because this is a feasibility study to assess effectiveness for a future RCT. We expect this will be of great importance to our team for future planning, but not of great significance to other researchers.
What supporting documents are/will be available?
Informed consent form
Ethical approval
'Other' documents specified
Baby informed consent form
How or where can supporting documents be obtained?
Type [1] 5130 0
Informed consent form
Citation [1] 5130 0
Link [1] 5130 0
Email [1] 5130 0
Other [1] 5130 0
Type [2] 5131 0
Ethical approval
Citation [2] 5131 0
Link [2] 5131 0
Email [2] 5131 0
Other [2] 5131 0
Type [3] 5132 0
Citation [3] 5132 0
Link [3] 5132 0
Email [3] 5132 0
Other [3] 5132 0
Baby consent form
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary