Does Hyperbaric Oxygen Therapy Lead to a Sustained Increase in Insulin
Description:
All participants will attend the Hyperbaric Medicine Unit on 5 occasions. Day 1 will be for
baseline assessment. Days 2 to 5 will be on consecutive days the following week. An overnight
fast will be required prior to each day.
Day 1. Baseline assessment. The participant will attend after an overnight fast at 0830 for
frequently sampled intravenous glucose tolerance test (FSIGT). Two IV lines will be placed
and baseline blood samples (30ml) are drawn for measurement of gluco-regulatory hormones and
metabolites at time 0. A glucose bolus is then administered through the antecubital vein IV
(300mg/kg, 25% Dextrose infused over 1-minute) at time 0. Blood sampling (3ml) is then
performed at 2,4,6,8,10,12,14,16,19,22,25,30,40,50,60,70,90,120,150,180 minutes after the
completion of the glucose bolus. Each blood sample is analysed for glucose and insulin. Total
blood collected during this procedure is approximately 60mls. A urine sample will be
collected. A meal will be provided.
Day 2. The following week, the participant will attend at 0800 after an overnight fast. They
will then be placed supine on a bed and a subcutaneous adipose tissue biopsy will be
performed using the technique of Bergstrom: after cleansing the skin on the abdomen lateral
to the umbilicus with chlorhexidine solution, and placing a fenestrated drape, anaesthesia is
administered (5mL of Xylocaine 2%, no adrenaline). A 7.5mm incision is made in the skin (#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 phosphate buffer solution and snap frozen in liquid
nitrogen. Upon completion of the biopsy the incision is closed with a sterile bandage, a
sterile dressing applied and pressure is applied for 10-minutes. Blood will be taken for
glucose, insulin and inflammatory markers (30mls). The participant will then sit in a chair
for 2-hours during a routine HBOT session from 0830-1030 (10:90:30 profile). After the first
HBOT, a further blood sample will be taken for inflammatory markers. Food will be provided.
Day 3. After an overnight fast, the participant will undergo a second routine HBOT session
from 0830-1030, followed by a second fat tissue biopsy. Blood will be taken for glucose,
insulin and inflammatory markers (30mls) before and after the HBOT. Food will be provided.
Day 4. After an overnight fast, the participant will undergo a third HBOT session from
0830-1030. This will be undertaken simultaneously with a FSIGT. The IV glucose bolus will be
administered at the beginning of the HBOT once the hyperbaric chamber has reached treatment
pressure (2 atmospheres absolute). On completion of the FSIGT, a meal will be provided.
Day 5. After an overnight fast, the participant will attend at 0830 for a fourth blood sample
for inflammatory markers. An FSIGT will be performed in room air outside the hyperbaric
chamber. A meal will be provided. A urine sample will be collected.
With blood taken during three FSIGTs together with 5 blood samples taken for inflammatory
markers, a total of about 330 mls of blood will be drawn over 9 days.
Condition:
Overweight and Obesity
Treatment:
Start Date:
July 2014
Sponsor:
University of Adelaide
For More Information:
https://clinicaltrials.gov/show/NCT02136615