Trial Review

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR


Registration number
ACTRN12614000239662
Ethics application status
Approved
Date submitted
28/02/2014
Date registered
6/03/2014
Date last updated
6/03/2014
Type of registration
Retrospectively registered

Titles & IDs
Public title
Treatment of type 2 diabetes with antioxidant vitamin C therapy
Scientific title
Placebo-controlled cross-over trial investigating high dose oral vitamin C supplementation in people with type 2 diabetes
Secondary ID [1] 284173 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 diabetes 291269 0
skeletal muscle insulin resistance 291306 0
Condition category
Condition code
Alternative and Complementary Medicine 291621 291621 0 0
Other alternative and complementary medicine
Metabolic and Endocrine 291659 291659 0 0
Diabetes

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Participants will orally consume either 2 x 500mg ascorbic acid or 2 x placebo capsules daily for four months. A 4-week wash-out period will separate treatments. Trial order will be randomized.
Intervention code [1] 288871 0
Treatment: Other
Comparator / control treatment
identical-looking placebo capsules containing gelatin
Control group
Active

Outcomes
Primary outcome [1] 291557 0
Measurement of insulin sensitivity using a euglycaemic, hyperinsulinaemic clamp coupled with the infusion of a stable glucose tracer (assessed using gas chromatography/mass spectrometry (GC/MS) methods)
Timepoint [1] 291557 0
Immediately before and immediately after both 4-month interventions.
Secondary outcome [1] 307072 0
Measurement of vitamin C status in skeletal muscle and plasma, measured using high performance liquid chromatography (HPLC).
Timepoint [1] 307072 0
Immediately before and immediately after both 4-month interventions.

Eligibility
Key inclusion criteria
Males and females with type 2 diabetes, no major medical illness apart from T2D, aged 35-70 years
Minimum age
35 Years
Maximum age
70 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
HbA1c >6.5% and <10.0%; total cholesterol <6.5mmol.L-1; triglycerides <4.0mmol.L-1; body mass index <35kg.m-2; systolic blood pressure <160mmHg; diastolic blood pressure <90mmHg; smoking, a history of cardiovascular, renal, respiratory or neurological disease; a heart murmur condition or bleeding disorder; haemochromatosis or iron overload disorders; insulin therapy, on oral anti-hyperglycaemic medications other than metformin (no greater than 2000mg total per day) or sulfonylureas and/or a dipeptidyl-peptidase-4 inhibitors; taking vitamin or herbal supplements during month prior to participation; taking medications known to influence insulin sensitivity; and if pregnant or planning a pregnancy during the trial period.

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)
Participants will undergo a screening session with our medical doctor during which a blood test and medical examination will occur to establish eligibility.
Participant trial order will be determined by a third party individual not directly involved in the trial. This individual will conceal treatments and determined the randomized allocation of treatments. Both vitamin C and placebo will be identical in appearance and sealed in identical opaque containers.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomized via coin toss
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering 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
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
2/05/2011
Actual
1/03/2012
Date of last participant enrolment
Anticipated
1/06/2012
Actual
1/02/2013
Date of last data collection
Anticipated
Actual
Sample size
Target
24
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 288803 0
University
Name [1] 288803 0
Deakin University
Country [1] 288803 0
Australia
Primary sponsor type
University
Name
Deakin University
Address
221 Burwood Hwy, Burwood Victoria 3125
Country
Australia
Secondary sponsor category [1] 287499 0
None
Name [1] 287499 0
Address [1] 287499 0
Country [1] 287499 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 290649 0
Deakin University Human Research Ethics Committee
Ethics committee address [1] 290649 0
221 Burwood Hwy, Burwood Victoria 3125
Ethics committee country [1] 290649 0
Australia
Date submitted for ethics approval [1] 290649 0
Approval date [1] 290649 0
14/12/2010
Ethics approval number [1] 290649 0
2010-256

Summary
Brief summary
Reactive oxygen species are the by-products of energy generation and thought to cause
problems with maintaining glucose levels in people with type 2 diabetes. Vitamin C (ascorbic
acid) is an antioxidant and is the most common vitamin supplement taken by adult Australians
(17% of the population). Its antioxidant effects might lower the levels of these reactive oxygen
species and improve the health of people with type 2 diabetes.
Aims:
To examine if antioxidant vitamin C supplementation reduces the levels of reactive oxygen
species and improves insulin sensitivity in skeletal muscle of people with type 2 diabetes.
Significance:
Studies that have examined the effectiveness of vitamin C supplementation in the treatment of
type 2 diabetes and insulin resistance in humans have so far produced conflicting and
disappointing results, due, at least in part, to inadequate study design and a failure to measure
the antioxidant action of vitamin C and insulin sensitivity at the key site of insulin action, which
is skeletal muscle.
The outcomes will likely contribute to new Australian health guidelines regarding the use of
antioxidant vitamin supplements for the treatment of insulin resistance in people with type 2
diabetes.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 46590 0
Dr Glenn Wadley
Address 46590 0
Deakin University, School of Exercise and Nutrition Sciences,
221 Burwood Hwy, Burwood, Vic, 3125
Country 46590 0
Australia
Phone 46590 0
+61 3 92446018
Fax 46590 0
Email 46590 0
[email protected]
Contact person for public queries
Name 46591 0
Dr Glenn Wadley
Address 46591 0
Deakin University, School of Exercise and Nutrition Sciences,
221 Burwood Hwy, Burwood, Vic, 3125
Country 46591 0
Australia
Phone 46591 0
+61 3 92446018
Fax 46591 0
Email 46591 0
[email protected]
Contact person for scientific queries
Name 46592 0
Mr Shaun Mason
Address 46592 0
Deakin University, School of Exercise and Nutrition Sciences,
221 Burwood Hwy, Burwood, Vic, 3125
Country 46592 0
Australia
Phone 46592 0
+61 392468285
Fax 46592 0
Email 46592 0
[email protected]

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

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
SourceTitleYear of PublicationDOI
EmbaseAscorbic acid supplementation improves skeletal muscle oxidative stress and insulin sensitivity in people with type 2 diabetes: Findings of a randomized controlled study.2016https://dx.doi.org/10.1016/j.freeradbiomed.2016.01.006
N.B. These documents automatically identified may not have been verified by the study sponsor.