High-dose vitamin E supplementation normalizes retinal blood flow and creatinine clearance in patients with type 1 diabetes

OBJECTIVE - To determine the effectiveness of vitamin E treatment in normal izing retinal blood flow and renal function in patients with <10 years of t ype 1 diabetes. RESEARCH DESIGN AND METHODS - An 8-month randomized double-masked placebo-c ontrolled crossover trial evaluated 36 type 1 diabetic and 9 nondiabetic su bjects. Subjects were randomly assigned to either 1,800 IU vitamin E/day or placebo for 4- months and followed, after treatment crossover, for a furth er 4 months. Retinal blood flow was measured using video fluorescein angiog raphy, and renal function was assessed using normalized creatinine clearanc e from timed urine collections. RESULTS - After vitamin E treatment, serum levels of vitamin E were signifi cantly elevated (P < 0.01) in both type 1 diabetic and control patients. He moglobin Al, was not affected by vitamin E treatment. Diabetic patient base line retinal blood flow (29.1 +/- 7.5 pixel(2)/s) was significantly (P = 0. 030) decreased compared with that of nondiabetic subjects (35.2 +/- 7.2 pix el(2)/s). After vitamin E treatment, diabetic patient retinal blood flow (3 4.5 +/- 7.8 pixel(2)/s) was significantly increased (P < 0.001) and was com parable with that of nondiabetic subjects. Additionally, vitamin E treatmen t significantly (P = 0.039) normalized elevated baseline creatinine clearan ce in diabetic patients. CONCLUSIONS - Oral vitamin E treatment appears to be effective in normalizi ng retinal hemodynamic abnormalities and improving renal function in type 1 diabetic patients of short disease duration without inducing a significant change in glycemic control. This suggests that vitamin E supplementation m ay provide an additional benefit in reducing the risks for developing diabe tic retinopathy or nephropathy.