Ascorbic acid supplementation improves postprandial glycaemic control and blood pressure in individuals with type 2 diabetes: Findings of a randomized cross-over trial

Diabetes Obes Metab. 2019 Mar;21(3):674-682. doi: 10.1111/dom.13571. Epub 2018 Dec 2.


Aim: The primary aim of this study was to investigate whether ascorbic acid (AA) supplementation improves postprandial glucose responses under free-living conditions in individuals with type 2 diabetes. A secondary aim was to investigate the effect of AA supplementation on blood pressure.

Materials and methods: A total of 31 individuals with type 2 diabetes (26 males and 5 females; aged 61.8 ± 6.8 years; duration of diabetes, 5.6 ± 4.6 years; HbA1c, 7.6% ± 0.7% [mean ± SD]) were enrolled in a randomized cross-over study involving 4 months of supplementation with oral AA (2 × 500 mg/d) or placebo. Participants wore continuous glucose monitors for 48 hours and consumed standardized meals pre- and post-supplementation. Measurements included postprandial glucose incremental areas under the curve (iAUC), duration of day in hyper- and hypo-glycaemia status, average 24-hour and daily postprandial glucose concentrations, HbA1c, insulin, blood pressure (BP) and oxidative stress (F2 -isoprostanes).

Results: Following AA supplementation, significant decreases were observed in daily postprandial glucose iAUC (-36%), in duration of day with hyperglycaemia (-2.8 h/d) and postprandial hyperglycaemia (-1.7 h/d), in average 24-hour glucose (-0.8 mmol/L) and daily postprandial glucose (-1.1 mmol/L) concentrations, in systolic (-7 mm Hg) and diastolic (-5 mm Hg) blood pressures and in a specific fraction of free plasma F2 -isoprostanes (-47 pg/mL) as compared to placebo.

Conclusions: Individuals with type 2 diabetes experienced improved postprandial and 24-hour glycaemia and decreased BP 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 BP control in individuals with type 2 diabetes.

Keywords: antidiabetic drug; clinical trial; continuous glucose monitoring (CGM); glycaemic control; randomised trial; type 2 diabetes.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Ascorbic Acid / therapeutic use*
  • Blood Glucose / drug effects*
  • Blood Glucose / metabolism
  • Blood Pressure / drug effects*
  • Cross-Over Studies
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / physiopathology
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Middle Aged
  • Placebos
  • Postprandial Period / drug effects


  • Blood Glucose
  • Placebos
  • Ascorbic Acid