Vitamin E Reduces Retinopathy And Nephropathy In Type I Diabetics

Nutrition Research Newsletter, Sept, 1999 by Sven-Erik Bursell, Allen C. Clermont, Lloyd Paul Aiello

Hyperglycemia, associated with diabetes mellitus, causes endothelial cell dysfunction resulting in decreased retinal blood flow. Diabetes is also associated with abnormal renal function. Previous clinical research has shown that hyperglycemia and diabetes restricts nitric oxide-related endothelium-dependent vasodilation and that treatment with antioxidants may alleviate this imbalance. Therefore vitamin E, a potent antioxidant, has been thought to potentially be of benefit in decreasing abnormalities associated with endothelial cell dysfunction, reducing complications associated with diabetes. Animal studies have shown vitamin E given to diabetic rats normalized retinal blood flow and glomerular filtration rate, even when experiencing chronic hyperglycemia.

A study was performed to evaluate the effectiveness of treating individuals with [is less than] 10 years of type I diabetes with vitamin E. It was hypothesized that vitamin E would be beneficial in normalizing retinal blood flow and renal function in these individuals. Researchers performed an eight-month randomized double-blind placebo-controlled crossover study utilizing 36 type I diabetics and nine nondiabetic subjects. Subjects were given either 1800 IU of vitamin E per day or a placebo pill for four months and then crossed over to the alternate therapy. Subjects were followed for an additional four months following the treatment period. Throughout the study, subjects' renal function was evaluated using normalized creatinine clearance from timed urine collection and retinal blood flow was tracked through the use of video fluorescein angiography.

After treatment with Vitamin E, diabetics' retinal blood flow was significantly increased and became comparable to that of the nondiabetic subjects. In addition, diabetics' elevated baseline creatinine clearance became significantly normalized following treatment with vitamin E.

Based on these findings, it appears that oral vitamin E supplementation is effective in improving type I diabetics' renal function and normalizing retinal blood flow. Vitamin E may prove to be beneficial in reducing the long-term complications associated with retinopathy and nephropathy in this population.

Sven-Erik Bursell, Allen C. Clermont, Lloyd Paul Aiello, et al., High-Dose Vitamin E Supplementation Normalizes Retinal Blood Flow and Creatinine Clearance in Patients With Type 1 Diabetes, Diabetes Care, 22(8): 1245-1251 (August 1999) [Correspondence: George L. King, MD, Research Division, Joslin Diabetes Center, 1 Joslin Place, Boston, MA 02215. E-mail: kingg@joslab.harvard.edu.]