Increased production of free radicals and depletion of antioxidants are commonly observed in diabetic patients. Based on animal studies, increased production of free radicals tends to persist even after blood glucose is tightly controlled. The rationale of using a potent antioxidant is based on the observation that increased oxidative stress associated with hyperglycemia can contribute to cellular injury leading to apoptosis; consequently, leading to diabetic retinopathy. Evidence from animal model showed that alpha lipoic acid (a potent antioxidant) was effective for decreasing the progression of diabetic retinopathy and in reducing free radicals.