Treatment of type 2 diabetes with antioxidant vitamin C therapy

Placebo-controlled cross-over trial investigating high dose oral vitamin C supplementation in people with type 2 diabetes

Status

Completed

Phases

Unknown

Study type

Interventional

Source

ANZCTR

Registry ID

ACTRN12614000239662

Enrollment

Registered

2014-03-06

Start date

2012-03-01

Completion date

2013-02-01

Last updated

2020-01-13

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

None listed

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.

Interventions

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.

Study design

Allocation

Randomised controlled trial

Intervention model

Crossover

Primary purpose

Treatment

Masking

Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

All

Age

35 Years to 70 Years

Healthy volunteers

Inclusion criteria

Males and females with type 2 diabetes, no major medical illness apart from T2D, aged 35-70 years

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.

Outcome results