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Trial registered on ANZCTR

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

Titles & IDs
Public title
The role of Vitamin C in managing type 2 diabetes: Vitamin C, Thiazolidinediones and their combined effect on
Scientific title
People with Type 2 diabetes currently treated with thiazolidinediones supplemented with Vitamin C and the combined effect on adiponectin as a therapeutic for metabolic disease.
Secondary ID [1] 262126 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 diabetes 265799 0
Condition category
Condition code
Metabolic and Endocrine 265955 265955 0 0

Study type
Description of intervention(s) / exposure
Dose escalation of Vitamin C supplementation, twice daily oral tablets, (500, 1000, 1500 and 2000 mg) for two weeks at each dose with no washout period in between. Vitamin C supplementation will be taken in addition to participants' existing thiazolidinedione treatment which will continue as usual.
Intervention code [1] 264541 0
Treatment: Other
Comparator / control treatment
Control group

Primary outcome [1] 266705 0
Increase in high molecular weight adiponectin assessed using a blood test and subsequent laboratory analysis of the sample.
Timepoint [1] 266705 0
At the start of the trial, fortnightly after each increase in Vitamin C dosage and then a fortnight after the final Vitamin C dosage is complete.
Secondary outcome [1] 276243 0
Timepoint [1] 276243 0

Key inclusion criteria
Female or male participants between the ages of 18 and 70 with non insulin dependent type 2 diabetes under TZD treatment (either rosiglitazone 4 – 8 mg or piogitazone greater than or equal 30 mg) with or without metformin.
HbA1C level 7 – 8.5 %.
Participant on stable diabetic therapy for three months prior to the intervention.
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
HbA1C level greater than 8.5 %
Participants must have a stable body weight (< 5% selfreported weight loss/gain) within last 3 months prior to enrolment.
Participants taking iron supplements.

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
Who is / are masked / blinded?

Intervention assignment
Other design features
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] 265024 0
Government body
Name [1] 265024 0
Queensland Department of Employment, Economic Development and Innovation
Address [1] 265024 0
Queensland Government
PO Box 15168, City East, Qld, 4002
Country [1] 265024 0
Primary sponsor type
Princess Alexandra Hospital
199 Ipswich Road Woolloongabba, Brisbane, Queensland, 4102
Secondary sponsor category [1] 264120 0
Name [1] 264120 0
University of Queensland
Address [1] 264120 0
The University of Queensland
Brisbane QLD 4072 Australia
Country [1] 264120 0

Ethics approval
Ethics application status
Ethics committee name [1] 267006 0
Metro South Health Service District Human Research Ethics Committee (EC00167)
Ethics committee address [1] 267006 0
Centres for Health Research Level 2, Building 35
Princess Alexandra Hospital
Ethics committee country [1] 267006 0
Date submitted for ethics approval [1] 267006 0
Approval date [1] 267006 0
Ethics approval number [1] 267006 0

Brief summary
Thiazolidinediones (TZD) are a class of drug commonly prescribed to manage type 2 diabetes. While the exact
mechanism of action is unknown, efficacy of the drug is closely correlated with improved circulating concentration of
a protein, adiponectin, secreted by fat tissue. Adiponectin is decreased in many diseases states including type 2
diabetes. Adiponectin is secreted as multimers of different sizes, termed low molecular weight (LMW) and high
molecular weight (HMW), and while an increase in circulating adiponectin is beneficial, it is more specifically an
increase in the HMW multimers that is correlated with improvement in health. An improvement in adiponectin profile refers to an increase in the proportion of the multimers present as HMW and may also be concomitant with an increase in total adiponectin.

Previous studies have demonstrated that high dose Vitamin C alone can improve glucose control in obese and
diabetic patients. Researchers involved with the proposed research project have demonstrated that combining
Vitamin C with TZD treatment has a synergistic effect on adiponectin profile in vitro in a human adipose cell line.
Vitamin C alone improves adiponectin profile 1.7 fold, while improvements are 5 fold over baseline when in
combination with TZD. Combining the evidence from previous studies and these in vitro observations
demonstrates a potential for combining TZD with high dose Vitamin C to get an improved treatment for managing
type 2 diabetes.

Research Design and Methods: Patients will have a two week wash out period to control vitamin c levels, and then
two weekly intervals on escalating doses of oral vitamin C for 8 weeks (4 doses, 500 mg / day, 1000 mg / day, 1500
mg / day and 2000 mg / day). Each patient will serve as their own control, with assessment of total and HMW
adiponectin at the beginning and end of the trial and at dose escalation points in between as primary endpoints.
Other indicators of improvement in metabolic parameters will also be monitored.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 32578 0
A/Prof Anthony Russell
Address 32578 0
Department of Diabetes and Endocrinology, Ground Floor Building 1, Princess Alexandra Hospital 199 Ipswich Road Woolloongabba QLD 4102
Country 32578 0
Phone 32578 0
+61 7 3240 5914
Fax 32578 0
Email 32578 0
Contact person for public queries
Name 15825 0
A/Prof Associate Professor Anthony Russell
Address 15825 0
Department of Diabetes and Endocrinology, Ground Floor
Building 1, Princess Alexandra Hospital
199 Ipswich Road
Woolloongabba QLD 4102
Country 15825 0
Phone 15825 0
+61 7 3240 5914
Fax 15825 0
Email 15825 0
Contact person for scientific queries
Name 6753 0
A/Prof Associate Professor Anthony Russell
Address 6753 0
Department of Diabetes and Endocrinology, Ground Floor
Building 1, Princess Alexandra Hospital
199 Ipswich Road
Woolloongabba QLD 4102
Country 6753 0
Phone 6753 0
+61 7 3240 5914
Fax 6753 0
Email 6753 0

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