The effect of vitamin C and/or E supplementations on type 2 diabetic adult males under metformin treatment: A single-blinded randomized controlled clinical trial

Diabetes Metab Syndr. 2018 Jul;12(4):483-489. doi: 10.1016/j.dsx.2018.03.013. Epub 2018 Mar 16.


Background and aim: Recently, there has been an increasing interest in the influence of antioxidant vitamins on the efficacy of oral hypoglycemic therapy in type 2 diabetic patients (T2DM). This single-blinded randomized controlled clinical trial aimed to investigate the effect of vitamin C and/or E supplementation on the efficacy of oral hypoglycemic therapy in T2DM Palestinian male patients from the Gaza Strip.

Methods: Forty T2DM male patients aged 40-60 years on metformin treatment were randomly divided into four groups, each group received an additional one of the following daily oral supplements for 90 days: placebo; vitamin C; vitamin E and vitamin C plus vitamin E. After overnight fasting, venous blood specimens were collected from all individuals into K3-EDTA tubes and serum tubes for measuring the biochemical and hematological parameters of the study at baseline and after 90 days of vitamins supplementation.

Results: The results revealed that vitamin C and/or E improve fasting blood sugar (FBS), HbA1c, lipid profile, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), reduced glutathione (GSH); and Quantitative Insulin Sensitivity Check Index (QISCI) compared with diabetic patients group that received placebo.

Conclusion: This study provided additional evidence on the beneficial effects of supplementing antioxidant vitamins in T2DM which could improve the clinical condition and attenuate or prevent diabetic pathogenesis and complications that, secondly to poor glycemic control, could attribute to the imbalance between the decline in the endogenous antioxidants and increasing production of the reactive oxygen species leading to the oxidant-mediated damage present in the diabetic context.

Keywords: Antioxidants; Insulin; Oxidative stress; Type 2 diabetes; Vitamin C; Vitamin E.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Antioxidants / metabolism
  • Ascorbic Acid / administration & dosage*
  • Biomarkers / analysis*
  • Blood Glucose / analysis
  • Case-Control Studies
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / pathology
  • Dietary Supplements*
  • Drug Synergism
  • Female
  • Follow-Up Studies
  • Glycated Hemoglobin / analysis
  • Hematologic Tests
  • Humans
  • Hypoglycemic Agents / therapeutic use
  • Insulin Resistance
  • Kidney Function Tests
  • Lipids / blood
  • Liver Function Tests
  • Male
  • Metformin / therapeutic use*
  • Middle Aged
  • Middle East
  • Oxidative Stress
  • Prognosis
  • Single-Blind Method
  • Vitamin E / administration & dosage*
  • Vitamins / administration & dosage*


  • Antioxidants
  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A
  • Hypoglycemic Agents
  • Lipids
  • Vitamins
  • hemoglobin A1c protein, human
  • Vitamin E
  • Metformin
  • Ascorbic Acid