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Trial registered on ANZCTR


Registration number
ACTRN12621000544875
Ethics application status
Approved
Date submitted
10/04/2021
Date registered
10/05/2021
Date last updated
2/06/2023
Date data sharing statement initially provided
10/05/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of the Gut Hormone Gastric Inhibitory Polypeptide (GIP) on Skeletal Muscle Blood Flow
Scientific title
Understanding the Role of Gastric Inhibitory Polypeptide (GIP) on Skeletal Muscle Blood Flow in Healthy Adults
Secondary ID [1] 303890 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Insulin resistance 321466 0
Diabetes 321506 0
Condition category
Condition code
Metabolic and Endocrine 319230 319230 0 0
Diabetes
Metabolic and Endocrine 319254 319254 0 0
Metabolic disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This study is a cross-over trial comparing the effect of gastric inhibitory polypeptide (GIP) versus saline on skeletal muscle blood flow. Each participant will receive both treatments (intravenous infusions) in the following order:

Infusions:
1) GIP - infused intravenously at 2 pmol/kg/min for 120 mins to raise plasma GIP levels.
2) Saline - infused intravenously for 120 mins.

A total of 13 healthy individuals with no history of cardiometabolic disease will be required to complete the study. Participants will be invited to attend an initial screening/familiarisation session, followed by 2 clinical testing sessions between 1 and 4 weeks apart. Participants will receive the GIP infusion first and then crossed-over to the saline infusion on the second clinical testing visit. In addition to GIP and saline infusion, all participants will also undergo a variable rate intravenous glucose tolerance test to mimic blood glucose excursions similar to an oral glucose tolerance test. The following measurements will be conducted:

Clinical chemistries and anthropometrics: Fasting clinical chemistries (glucose, insulin, lipid profile, HbA1c) and body composition (height, weight) will be measured. Clinical chemistries will be assessed via an accredited pathology laboratory.

Microvascular blood flow responses in skeletal muscle: Microvascular blood flow will be measured via contrast-enhanced ultrasound imaging of the thigh muscle at baseline (0 min) and at 60 min and 120 min post-GIP and -saline infusion.

Femoral artery blood flow responses: Femoral artery blood flow will be measured via 2D and Doppler ultrasound imaging at baseline (0 min) and at 60 min and 120 min post-GIP and -saline infusion.

Metabolic and hormonal responses: Blood glucose, plasma insulin and plasma GIP levels will be measured at regular time points over 120 mins during the infusion of GIP and saline.
Intervention code [1] 320206 0
Treatment: Other
Comparator / control treatment
Saline - infused intravenously
Control group
Placebo

Outcomes
Primary outcome [1] 327108 0
Change in skeletal muscle microvascular blood flow during GIP and Saline infusion.
Timepoint [1] 327108 0
Skeletal muscle (thigh) microvascular blood flow will be measured at 0, 60 and 120 mins post-GIP and -Saline infusion using contrast-enhanced ultrasound.
Secondary outcome [1] 393833 0
Change in femoral artery blood flow during GIP and Saline infusion.
Timepoint [1] 393833 0
Femoral artery blood flow will be measured at 0, 60 and 120 mins post-GIP and -Saline infusion using 2D and Doppler ultrasound.
Secondary outcome [2] 393834 0
Change in blood glucose levels
Timepoint [2] 393834 0
Blood samples will be taken to measure blood glucose levels. Samples will be collected at baseline (0 min) and at 5, 10, 15, 20, 30, 40, 50, 60, 80, 90, 100, 110, and 120 min following commencement of the infusion. The glucose area under the time curve will also be calculated.
Secondary outcome [3] 393835 0
Change in plasma insulin levels
Timepoint [3] 393835 0
Blood samples will be taken to measure plasma insulin levels. Samples will be collected at baseline (0 min) and every 10-20 mins over 120 mins post-infusion. The insulin area under the time curve will also be calculated. Plasma insulin levels will be assessed via ELISA.
Secondary outcome [4] 393921 0
Changes in plasma gastric inhibitory peptide (GIP) levels
Timepoint [4] 393921 0
Blood samples will be taken to measure plasma GIP levels. Samples will be collected at baseline (0 min) and every 10-20 mins over 120 mins post-infusion. The GIP area under the time curve will also be calculated. Plasma GIP levels will be assessed via ELISA.

Eligibility
Key inclusion criteria
1. Aged 18-50 years
2. Body mass index (BMI) range 18.5-30kg/m2
3. Normotensive (seated brachial blood pressure <140/90 mmHg)
4. Provided signed informed consent to participate in the study
Minimum age
18 Years
Maximum age
50 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
1. Aged <18 >50 years
2. BMI range <18.5 >30kg/m2
3. Brachial blood pressure >140/90 mm/Hg, or taking an anti-hypertensive for elevated blood pressure.
4. A first degree relative (eg. parent) with diagnosed Type 2 diabetes
5. >1 grandparent with diagnosed Type 2 diabetes
6. Personal history of any of the following:
- Diabetes
- Myocardial infarction (MI)
- Cardiovascular disease
- Stroke
- Peripheral artery disease
- Pulmonary disease
- Arthritis muscular skeletal disease
- Liver disease
7. Malignancy within the past 5 years
8. Current smoker
9. Pregnancy/ lactation
10. Women with an irregular menstrual cycle

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?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis
Data will be checked for normality. Student paired t-tests or repeated measures ANOVA will be used to compare between treatment groups (GIP versus saline). Statistical analysis will be conducted at the 95% level of significance (p = 0.05). Where possible, data analysis will be conducted in a blind fashion.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
12/05/2021
Actual
26/10/2021
Date of last participant enrolment
Anticipated
22/12/2023
Actual
Date of last data collection
Anticipated
22/12/2023
Actual
Sample size
Target
13
Accrual to date
4
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 308280 0
University
Name [1] 308280 0
Deakin University
Country [1] 308280 0
Australia
Primary sponsor type
University
Name
Deakin University
Address
221 Burwood Highway, Burwood, VIC 3125
Country
Australia
Secondary sponsor category [1] 309096 0
None
Name [1] 309096 0
Address [1] 309096 0
Country [1] 309096 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 308255 0
Deakin University Human Ethics Committee
Ethics committee address [1] 308255 0
221 Burwood Highway, Burwood, VIC, 3125
Ethics committee country [1] 308255 0
Australia
Date submitted for ethics approval [1] 308255 0
15/11/2020
Approval date [1] 308255 0
07/01/2021
Ethics approval number [1] 308255 0
2020-401

Summary
Brief summary
After consuming a meal, blood glucose levels rise which results in the pancreas secreting the hormone insulin. Insulin increases blood flow in skeletal muscle (similar to exercise) and this blood flow effect helps deliver the glucose to the muscle for storage (1, 2). We have recently shown that if someone consumes only glucose in their meal this results in an impairment in muscle blood flow (3). We have recently built on this finding to show that when matched for blood glucose levels, intravenously infused glucose (which by-passes the gut) has the opposite effect and stimulates muscle blood flow (not published). Therefore, our data suggests that a gut-derived factor could be regulating the impaired muscle blood flow observed with orally ingested glucose. The aim of this project is to investigate the effects of one of these gut-hormones called Gastric Inhibitory Polypeptide (GIP) on muscle blood flow. Findings from this study will enhance our knowledge and understanding of blood flow regulation after a meal and has implications in the consumption of high glycemic-index food and drinks.

References:
1. Clark MG, Wallis MG, Barrett EJ, Vincent MA, Richards SM, Clerk LH, et al. Blood flow and muscle metabolism: a focus on insulin action. American Journal of Physiology-Endocrinology And Metabolism. 2003;284(2):E241-E58.
2. Keske MA, Dwyer RM, Russell RD, Blackwood SJ, Brown AA, Hu D, et al. Regulation of microvascular flow and metabolism: An overview. Clinical and Experimental Pharmacology and Physiology. 2017;44(1):143-9.
3. Russell RD, Hu D, Greenaway T, Sharman JE, Rattigan S, Richards SM, et al. Oral Glucose Challenge Impairs Skeletal Muscle Microvascular Blood Flow in Healthy People. American Journal of Physiology-Endocrinology and Metabolism. 2018.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 110094 0
Prof Michelle Keske
Address 110094 0
Institute for Physical Activity and Nutrition (IPAN), Deakin University, 221 Burwood Highway, Burwood, VIC 3125
Country 110094 0
Australia
Phone 110094 0
+61 3 9246 8850
Fax 110094 0
Email 110094 0
[email protected]
Contact person for public queries
Name 110095 0
Michelle Keske
Address 110095 0
Institute for Physical Activity and Nutrition (IPAN), Deakin University, 221 Burwood Highway, Burwood, VIC 3125
Country 110095 0
Australia
Phone 110095 0
+61 3 9246 8850
Fax 110095 0
Email 110095 0
[email protected]
Contact person for scientific queries
Name 110096 0
Michelle Keske
Address 110096 0
Institute for Physical Activity and Nutrition (IPAN), Deakin University, 221 Burwood Highway, Burwood, VIC 3125
Country 110096 0
Australia
Phone 110096 0
+61 3 9246 8850
Fax 110096 0
Email 110096 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
The results will be published in a journal article. Due to confidentiality we will not be providing individual data.


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
11319Ethical approval    381759-(Uploaded-09-04-2021-12-35-15)-Study-related document.pdf



Results publications and other study-related documents

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