Introduction: Diabetes is regarded as a metabolic disease and one of its characteristics is hyperglycemia, which could lead to fatal complications. One of the criteria for diagnosis and control of diabetes is measuring fasting plasma glucose and glycosylated hemoglobin. In addition, vitamin C can improve glucose tolerance. Therefore, this study was conducted to evaluate the effect of vitamin C on fasting plasma glucose and glycosylated hemoglobin (HbA1c) in patients with type II diabetes.

Methodology: This controlled clinical trial was conducted on 74 eligible samples, randomly divided into two groups of test and control. Firstly, fasting plasma glucose and HbA1c were measured, followed by the treatment of the test group with vitamin C pills for three months. Data analysis was performed in SPSS version 19 using independent and paired t-tests.

Results: Evaluation of the final results revealed a significant decrease in biochemical markers in the control group, compared to the test group. In other words, a significant difference was observed between the study groups after the intervention.

Conclusion: According to the results of this study, vitamin C could reduce fasting plasma glucose and HbA1c in patients with type II diabetes through competition with glucose. This impact of vitamin C could be applied to control the pathogenic mechanism of protein glycation in diabetes after more accurate evaluations in this regard.