None listed
Conditions
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.
Interventions
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.
Sponsors
Princess Alexandra Hospital
Study design
Allocation
Non-randomised trial
Primary purpose
Treatment
Eligibility
Sex/Gender
All
Age
18 Years to 70 Years
Healthy volunteers
No
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.
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.
Outcome results
None listed