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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Hyperbaric Oxygen Therapy and Insulin Resistance.
Scientific title
Effect of one session of Hyperbaric Oxygen Therapy on insulin resistance in overweight men and women.
Secondary ID [1] 282338 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Insulin sensitivity 288886 0
Condition category
Condition code
Metabolic and Endocrine 289229 289229 0 0
Diet and Nutrition 289255 289255 0 0

Study type
Description of intervention(s) / exposure
Visit 0 (Pre-clamp) and Visit 3 (Post-clamp) - Blood samples and subcutaneous adipose tissue biopsy:
Subject will be seated comfortably in a chair for a 2-hour period. An IV cannula will be inserted into a vein in the forearm, and blood will be taken for analysis of fasting glucose and insulin time (t) = 0 min, and for cytokines at t = 0, 60 and 120 mins. The adipose tissue biopsy will then be performed. After cleansing the skin on the abdomen lateral to the umbilicus with chlorhexidine solution, and placing a fenestrated drape, anaesthesia will be administered (5ml of Xylocaine 2%, no adrenaline) via subcutaneous injection. A 0.75cm incision is made in the skin using a #11 scalpel, and a 5mm Bergstrom needle inserted to collect approximately 250mg of adipose tissue with suction. Two or three passes will be used to obtain approximately 500mg of adipose tissue. The sample is washed in sterile 0.9% saline and snap frozen in liquid nitrogen. Upon completion of the biopsy, pressure is applied and the incision closed with a sterile 'Steri-strip'.

Visit 1 and Visit 2 - Hyperinsulinaemic euglycaemic clamp:
Two intravenous cannulae are inserted into veins in contralateral forearms using local anaesthetic (lignocaine 1%). A baseline blood sample is taken to assess fasting glucose, and a primed insulin infusion is started for assessment of insulin sensitivity by hyperinsulinemic euglycemic clamp (80mU/m2/min) for 3.5 hours. Blood samples (<2mls) are obtained at 5-10 minute intervals so that blood glucose can be maintained at 5mmol/L with a variable infusion of 25% Dextrose, and a trained individual will be present for the duration of the clamping procedure. The steady state glucose infusion rate is calculated over the final 30 minutes of the clamp and adjusted for fat free mass by DXA. Immediately post-clamp, volunteers are given orange juice and high carbohydrate lunch, and the glucose infusion is maintained on a halving scale for 5 minutes each for at least 20 minutes. Blood sugar levels are monitored every 10-15 minutes for 45-60 minutes.

Visit 2 and Visit 3 - Hyperbaric oxygen (HBO) therapy:
Subject will be seated comfortably in a chair and wheeled into the chamber. The HBO session will involve compression to 2 atmospheres absolute, breathing 100% oxygen via a 'hood' gas delivery system for 90 minutes, and a linear decompression to 1 atmosphere absolute over 30 minutes. During visit 2, the 2-hour HBO treatment will occur during the second and third hours of the clamp. During visit 3, the HBO treatment will occur during the 2 hours immediately preceding the biopsy.

Visit 4 - Blood samples:
Subject will be seated comfortably, and a single blood sample will be taken for analysis of fasting glucose, insulin and cytokines.

Visits 1 to 4 will occur on consecutive days, and visit 0 will occur 1 to 2 weeks beforehand.
Intervention code [1] 286954 0
Treatment: Devices
Comparator / control treatment
No treatment: Subjects will undergo the insulin clamp and adipose tissue biopsy without hyperbaric oxygen therapy.
Control group

Primary outcome [1] 289349 0
Insulin sensitivity, as measured by the hyperinsulinaemic euglycaemic clamp.
Timepoint [1] 289349 0
The clamps will be used to measure insulin sensitivity on two separate days. The first clamp will occur without hyperbaric oxygen (HBO) treatment, and act as a 'basline' measurement, while the second clamp will occur the following day with a 2-hour HBO treatment starting after the first hour.
Primary outcome [2] 289350 0
Inflammation and angiogenesis associated with insulin resistance, as measured by levels of various cytokine markers (CRP, MCP1, TNFa, IL-6, ICAM-1, VEGFa and PDGF) using various serum and plasma assays.
Timepoint [2] 289350 0
At t=0min, 60min and 120min of a 2 hour period with or without hyperbaric oxygen exposure.
Secondary outcome [1] 302285 0
Gene expression related to inflammation and angiogenesis present in adipose tissue samples will be measured using Q-PCR.
Timepoint [1] 302285 0
At baseline, and after one 2-hour hyperbaric oxygen exposure.

Key inclusion criteria
1. Overweight and obesity (BMI 25-35kg/m2)
2. Assessed fitness to enter hyperbaric chamber
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Personal history of Diabetes or major psychiatric disorders,
2. Use of prescribed or non-prescribed medications which may affect glucose homeostasis (eg steroids)
3. Uncontrolled asthma, current fever, upper respiratory infections
4. Individuals who regularly perform high intensity exercise (>2 week)
5. Pregnancy, lactation (breast feeding), women who are planning to become pregnant.
6. Current intake of > 140g alcohol/week
7. Current smokers of cigarettes/cigars/marijuana
8. Current intake of any illicit substance
9. Experience claustrophobia in confined spaces
10. Has donated blood within past 3-months
11. Has been involved in any other study within the past 3-months
12. Unable to comprehend study protocol
13. Any other contraindication to HBOT (eg Eustachian tube dysfunction making middle ear inflation ineffective)

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

Intervention assignment
Single group
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 287096 0
Name [1] 287096 0
Royal Adelaide Hospital
Address [1] 287096 0
North Tce, Adelaide SA 5000
Country [1] 287096 0
Primary sponsor type
David Wilkinson
Hyperbaric Medicine Unit
Dept of Anaesthesia and Intensive Care
Royal Adelaide Hospital
North Tce, Adelaide SA 5000
Secondary sponsor category [1] 285873 0
Name [1] 285873 0
Leonie Heilbronn
Address [1] 285873 0
University of Adelaide
Discipline of Medicine
Eleanor Harrald Building
Frome Rd, Adelaide SA 5000
Country [1] 285873 0

Ethics approval
Ethics application status

Brief summary
In a recent series of studies performed by our group, we have shown that exposure to hyperbaric oxygen (HBO) leads to an increase in insulin sensitivity in male subjects and that this improvement can be measured in all men, not just those with diabetes. The aim of this study is to investigate the time course of this effect and explore the mechanisms involved when exposure to HBO induces an increase in peripheral insulin sensitivity. This study will also test whether the same thing happens in female subjects.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 39298 0
Dr David Wilkinson
Address 39298 0
Hyperbaric Medicine Unit
Dept of Anaesthesia and Intensive Care
Royal Adelaide Hospital
North Tce, Adelaide SA 5000
Country 39298 0
Phone 39298 0
Fax 39298 0
Email 39298 0
Contact person for public queries
Name 39299 0
Ms Briohny Bartlett
Address 39299 0
University of Adelaide
Discipline of Medicine
Level 6, Eleanor Harrald Building
Frome Rd, Adelaide SA 5000
Country 39299 0
Phone 39299 0
Fax 39299 0
Email 39299 0
Contact person for scientific queries
Name 39300 0
Dr David Wilkinson
Address 39300 0
Hyperbaric Medicine Unit
Dept of Anaesthesia and Intensive Care
Royal Adelaide Hospital
North Tce, Adelaide SA 5000
Country 39300 0
Phone 39300 0
Fax 39300 0
Email 39300 0

No information has been provided regarding IPD availability
Summary results
No Results