Background and Aim: There is growing evidence for the useful role of antioxidants in decreasing blood glucose, increasing of insulin sensitivity and prevention of further exacerbation of the development and progression of diabetes type 2. The purpose of the present study was to determine the effect of oral administration of alpha-lipoic acid (ALA), as an antioxidant, on fasting blood sugar (FBS), insulin level and insulin resistance in type 2 diabetic patients.

  Materials and Methods: Fifty-seven type 2 diabetic patients (14 males and 43 females) with the mean age of 53.5 ± 8.6 years were involved in this clinical trial. Upon arrival, the subjects were randomly divided into experimental (n=29) and control (n=28) groups. The experimental group received 300 mg alpha-lipoic acid daily, while the control group received 3 placebo tablets daily for eight weeks. Body mass index (BMI), FBS and insulin level of the subjects were measured at the beginning and at the end of the study. The obtained data were analyzed by means of paired t-test and independent t-test, using SPSS software.

  Results: Comparison of weight and BMI between the two groups, before and after intervention, did not reveal a significant difference. The result of the study showed a significant decrease in FBS and insulin resistance level in the experimental group (P=0.0001 and P=0.04, respectively). The level of fasting insulin decreased a little but this was not significant (P=0.43). The mean of changes in FBS (P=0.001) and insulin resistance (P=0.013) before and after study showed a significant difference between the two groups.

  Conclusion: Alpha-lipoic acid supplement is useful in decreasing insulin resistance and can be effective in the prevention of diabetic complications.