Efficacy of supplementary vitamins C and E on anxiety, depression and stress in type 2 diabetic patients: a randomized, single-blind, placebo-controlled trial

Pak J Biol Sci. 2013 Nov 15;16(22):1597-600. doi: 10.3923/pjbs.2013.1597.1600.


Diabetes mellitus as one of the most prevalent endocrine disease is associated with high oxidative stress. Anxiety, stress and depression are common neuropsychiatric features in diabetic patients. Hyperglycemia leads to increased oxidative stress which in turn diminishes antioxidant defense system. On the other hand oxidative stress is the leading cause of depression and anxiety disorders. Thus, it seems that diabetes could accelerate the trend of psychiatric diseases. In this randomized single-blind study, evaluation of the effects of two antioxidants (vitamin C and vitamin E) was done on Stress, depression and anxiety levels in 45 diabetic patients for six weeks. The patients were randomly divided in three groups of vitamin E (400 IU day(-1)), vitamin C (1000 mg day(-1)) and placebo. DASS-21 (Depression Anxiety Stress Scales 21-item) questionnaire items were read to each patient and completed by the main investigator of this study before and after six weeks of supplementation. The scores of depression, anxiety and stress were evaluated separately based on the DASS questionnaire. The results showed a significant decrease in anxiety level (p = 0.005) in vitamin C group compared to other groups but there were no significant differences between groups in terms of changes in stress and depression scores. In conclusion, this study suggests that short-term supplementation of vitamin C is safe and beneficial for reducing anxiety levels in diabetic patients through alleviating oxidative damage.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Analysis of Variance
  • Antioxidants / therapeutic use*
  • Anxiety / diagnosis
  • Anxiety / drug therapy*
  • Anxiety / etiology
  • Anxiety / metabolism
  • Ascorbic Acid / therapeutic use*
  • Depression / diagnosis
  • Depression / drug therapy*
  • Depression / etiology
  • Depression / metabolism
  • Diabetes Mellitus, Type 2 / complications*
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / psychology
  • Dietary Supplements*
  • Female
  • Humans
  • Iran
  • Male
  • Middle Aged
  • Oxidative Stress / drug effects
  • Psychiatric Status Rating Scales
  • Single-Blind Method
  • Surveys and Questionnaires
  • Time Factors
  • Treatment Outcome
  • Vitamin E / therapeutic use*


  • Antioxidants
  • Vitamin E
  • Ascorbic Acid