Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12614000742673
Ethics application status
Approved
Date submitted
16/06/2014
Date registered
14/07/2014
Date last updated
3/10/2014
Type of registration
Prospectively registered

Titles & IDs
Public title
Improving glucose monitoring with lifestyle intervention for individuals with impaired glucose tolerance
Scientific title
Determining precision of continuous glucose monitors for quantifying 24 h glycemia in response to dietary modification and exercise in men with impaired glucose tolerance.
Secondary ID [1] 284698 0
Nil
Universal Trial Number (UTN)
U1111-1157-5167
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Impaired glucose tolerance 292052 0
Condition category
Condition code
Metabolic and Endocrine 292386 292386 0 0
Diabetes

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This study will utilise a within subject (cross-over) design and each 3 day intervention period will be separated by a minimum one week washout period. Each participant will undertake four separate experimental trials: (1) a series of low glycemic index (GI) meals (2) a series of high glycemic meals (3) low intensity intermittent training (LIT) and (4) high intensity interval training (HIT). A description of the dietary and exercise interventions are provided below.

Continuous glucose monitor: The glucose sensor (Medtronic EnliteTM) will be inserted on the side of the torso under the skin 24 h prior to each experimental trial. The device will remain in situ for 72 hours and is water proof and does not prevent bathing or swimming activities. This will be repeated for each of the four experimental trials. Insertion of the microdialysis fibre into the superficial subcutaneous adipose tissue does not require anaesthetic, is minimally invasive and barely discernible. The glucose sensor measures interstitial glucose concentration and is connected to the digital recorder (Medtronic iProTM2). They are both secured to the skin surface by medical adhesive dressing (3MTM Tegaderm) and require no further intervention until removed.

Dietary Intervention: All meals and snacks will be provided during each 12 h experimental trial. The low and high GI diets will be matched for carbohydrate (60%), protein (10-15%) and fat (25-30%) content but will differ in the glycemic index. The glycemic index of breakfast, lunch and dinner of the low and high GI diet will differ by ~40, 40 and 10 U, respectively. Breakfast, lunch and dinner will each be separated by 5 h and consumed at ~0730, 1230 and 1730 h during each experimental trial.

Exercise Intervention: All meals and snacks from the high GI diet trial will be provided during each exercise trial. The two exercise sessions will be performed on separate occasions and will be matched for total mechanical work but will differ in the exercise intensity and duration. The LIT protocol will involve 3 x 15 minute bouts of cycling performed at 40% peak power output (PPO). One 15 minute bout of exercise will be undertaken prior to each meal (5 h recovery period between exercise bouts). The HIT protocol will involve a 5 minute warm up and 12 × 60 s repetitions of cycling at 80% PPO, each interspersed with 60 s active recovery at 40% PPO. The single HIT session will be undertaken before the first meal (breakfast) during the experimental trial. All exercise will be performed on a stationary indoor cycle ergometer. Heart rate (HR) and rating of perceived exertion (RPE) will be measured during exercise.

Blood samples will be taken at rest prior to commencing the experimental trial, and at regular intervals throughout the day. Blood will be extracted via a catheter placed into a forearm vein.
Intervention code [1] 289486 0
Lifestyle
Comparator / control treatment
This study will utilise a within subject (cross-over) design and compare glucose modulation and measurement precision with various diet and exercise modalities. In addition, a free-living period where the continuous glucose monitor will be implanted 24 h prior to each experimental trial will also be used as a comparator. The participants glucose profile, habitual diet and physical activity will be monitored.

There is no control group; each participant will act as their own control.
Control group
Active

Outcomes
Primary outcome [1] 292250 0
Accuracy of continuous glucose monitor (CGM).

Glucose values recorded by the CGM will be compared to reference values (venous blood sample) during modulation of glucose excursion in response to dietary intake and exercise throughout a 24 h period. Associations between techniques will be determined using intraclass correlations coefficient (ICC) and differences between techniques will be determined by Bland Altman Plots.
Timepoint [1] 292250 0
The CGM will record 288 glucose values in 24 h for each experimental trial. A total of 22 samples of venous blood will be collected at baseline (prior to exercise), 0, 15, 30, 45, 60, 90, 150, 210 and 270 minutes after meals 1 and 2 (breakfast and lunch) and 0, 15, 30, 45, 60 and 90 minutes after meal 3 (dinner).
Primary outcome [2] 292272 0
Postprandial glycemia (PPG), (0-2 h) and postabsorptive (2-4 h) glucose response after divergent meal and exercise protocols.

Glucose values recorded by the continuous glucose monitor every 5 minutes during the 4 h period will be used to calculate the total area under the curve (AUC).
Timepoint [2] 292272 0
Three x four hour periods following breakfast, lunch and dinner during each experimental trial.
Secondary outcome [1] 308601 0
Average 24 h blood glucose

Measured by averaging the 288 glucose values recorded by the CGM in 24 hours.
Timepoint [1] 308601 0
24 h for each experimental trial
Secondary outcome [2] 308602 0
Prevalence of hyperglycemia i.e. blood glucose value > 10 mmol/L.

Measured by the total duration of hyperglycemic episodes in 24 h, indicated by glucose values recorded by the CGM.
Timepoint [2] 308602 0
24 h for each experimental trial

Eligibility
Key inclusion criteria
Fasting plasma glucose value between 5.6-6.9 mmol/L
HbA1c value between 5.7-6.4%
Physically inactive (< 30 minutes of physical activity per week)
Body mass index < 29.9 kg/m2
Minimum age
20 Years
Maximum age
55 Years
Sex
Males
Can healthy volunteers participate?
No
Key exclusion criteria
Obesity (BMI > 30kg/m2)
Uncontrolled hypertension (> 160 mmHg systolic and/or > 100 mmHg diastolic)
History of cardiovascular disease
Liver disease
Contraindications to exercise training


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)
Potential participants will contact researchers via the contact details provided on an advertisement for the study. They will then be provided with a participant information sheet and following provision of informed consent will undergo medical screening including evaluation of inclusion and exclusion criteria. Allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be assigned to undertake the four experimental trials in a randomised, counterbalanced design using a Latin Square procedure.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis
Statistical analysis will be completed using SPSS v21.0. Data will be analysed using repeated measures analysis of variance with Bonferroni post-hoc testing. The primary outcome measures in the current study are changes in glucose concentration. Based on data reported in similar studies (Figueira et al., 2013; Van Dijk et al., 2013; Oberlin et al., 2014) in order to detect the smallest clinically relevant differences for the change in glucose concentration and area under the curve (effect size 0.8, P<0.05) a sample size of n=8-10 is required. To ensure the proposed study is sufficiently powered we will recruit 16 participants. This sample size exceeds the minimum sample requirements based on the power analysis and are similar to Little et al. (2011) who undertook a comparable study.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
1/09/2014
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
16
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment postcode(s) [1] 8210 0
4059 - Kelvin Grove

Funding & Sponsors
Funding source category [1] 289319 0
Charities/Societies/Foundations
Name [1] 289319 0
The George Weaber Foundation
Country [1] 289319 0
Australia
Primary sponsor type
Individual
Name
Stephanie Zietek
Address
Queensland University of Technology (QUT)
Institute of Health and Biomedical Innovation (IHBI)
60 Musk Ave
Kelvin Grove, QLD 4059
Country
Australia
Secondary sponsor category [1] 287990 0
Individual
Name [1] 287990 0
Dr Vernon Coffey
Address [1] 287990 0
Queensland University of Technology (QUT)
Institute of Health and Biomedical Innovation (IHBI)
60 Musk Ave
Kelvin Grove, QLD 4059
Country [1] 287990 0
Australia
Other collaborator category [1] 277982 0
Individual
Name [1] 277982 0
Prof Nuala Byrne
Address [1] 277982 0
Bond University Institute of Health & Sport
Promethean Way
Robina, QLD 4229
Country [1] 277982 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 291082 0
Queensland University of Technology: University Human Research Ethics Committee (EC00171)
Ethics committee address [1] 291082 0
Victoria Park Rd
Kelvin Grove QLD 4059
Ethics committee country [1] 291082 0
Australia
Date submitted for ethics approval [1] 291082 0
20/05/2014
Approval date [1] 291082 0
06/08/2014
Ethics approval number [1] 291082 0
1400000394

Summary
Brief summary
This study aims to establish the validity and precision of continuous glucose monitors (CGM's) for determining glycemia in response to diet and exercise. CGM's are a new, minimally invasive technology that provide greater insight into the direction, magnitude and frequency of daily glucose fluctuations. Postprandial glycemia is a significant determinant of glycemic control in individuals with impaired glucose tolerance. Given the prevalence of diabetes, it is important to identify effective lifestyle interventions to treat and manage pre-diabetes, and quantify the capacity to monitor daily variations in glucose control. We hypothesise that CGM precision will be reduced during high glucose excursions and strenuous exercise, and that high intensity exercise will be superior for promoting the return of glycemia to basal levels.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 48830 0
Miss Stephanie Zietek
Address 48830 0
Institute of Health and Biomedical Innovation (IHBI)
60 Musk Ave
Kelvin Grove, QLD 4059
Country 48830 0
Australia
Phone 48830 0
+61 7 3138 6095
Fax 48830 0
Email 48830 0
s.zietek@qut.edu.au
Contact person for public queries
Name 48831 0
Miss Stephanie Zietek
Address 48831 0
Institute of Health and Biomedical Innovation (IHBI)
60 Musk Ave
Kelvin Grove, QLD 4059
Country 48831 0
Australia
Phone 48831 0
+61 7 3138 6095
Fax 48831 0
Email 48831 0
s.zietek@qut.edu.au
Contact person for scientific queries
Name 48832 0
Dr Vernon Coffey
Address 48832 0
Institute of Health and Biomedical Innovation (IHBI)
60 Musk Ave
Kelvin Grove, QLD 4059
Country 48832 0
Australia
Phone 48832 0
+61 7 3138 6087
Fax 48832 0
Email 48832 0
vernon.coffey@qut.edu.au

No information has been provided regarding IPD availability


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

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