Efficacy of ascorbic acid in improving glycaemic control in type 2 diabetes

The main aim of this study was to investigate whether ascorbic acid (AA) supplementation improves glycaemic control under free-living conditions in individuals with type 2 diabetes. We also investigated effects of AA supplementation on blood pressure. Thirty-one individuals with type 2 diabetes (26 males and 5 females; average age 62 years; average duration of diabetes 5.6 years) and moderate glucose control (average HbA1c 7.6%) were enrolled in a randomized cross-over study involving 4 months of supplementation with oral AA (2 × 500 mg/day) or placebo. Participants took both AA and placebo, however the order of each 4-month period was randomized and blinded to both participants and researchers. AA supplementation significantly decreased the average daily post-meal glucose response, the duration of day spent in hyperglycaemia, the average 24-hour glucose concentration, blood pressure, and a marker of oxidative stress in blood as compared to placebo. Overall, individuals with type 2 diabetes experienced improved post-meal and 24-hour glucose levels and decreased blood pressure after 4 months of AA supplementation as compared to placebo. These findings offer evidence for the proposed use of AA as an adjunct therapy to improve glycaemic and blood pressure control in individuals with type 2 diabetes.