The effect of long term, high dose ascorbic acid supplementation on blood glucose concentration levels was investigated upon in 17 healthy and 19 diabetic patients measuring their glycated hemoglobin (HbA1c) levels. Ascorbic acid treatment resulted in a significant reduction in HbA1c (7 and 9% of initial values in control and diabetic groups, respectively). The extent of the reduction was dependent on initial glycated hemoglobin levels in both groups, therefore, the effect of ascorbic acid was more pronounced in the diabetic group. Ascorbic acid supplementation elevated the plasma levels of reduced glutathione by 81 and 108 %. in control and diabetic groups, respectively. It is suggested that the increase of serum antioxidant glutathione and the decrease of glycated hemoglobin after long term ascorbic acid supplementation are related to each other.

Keywords: diabetes, glycation, Ascorbic Acid, Glucose, ascorbate