Vitamin B6 has been expected to prevent the progression of diabetic retinopathy. Previous studies reported that treatment with vitamin B6 protected against capillary dropout in a mouse model of diabetes and low serum vitamin B6 levels were associated with retinal vein occlusion in healthy individuals. However, data on this topic in patients with diabetes are sparse. As part of a nationwide cohort study we investigated the relationship between vitamin B6 intake and the incidence of diabetic retinopathy in Japanese patients with type 2 diabetes aged 40-70 years with HbA1c≥6.5%. The present analysis was conducted among 22Japanese patients with type 2 diabetes from outpatient clinics in 59 university and general hospitals in Japan. Analyzed were 1516 responders to a baseline dietary survey assessed by the Food Frequency Questionnaire based on food groups. Primary outcome was the 8-year risk of a diabetic retinopathy event. Cox regression analyses estimated hazard ratios (HRs) for dietary intake adjusted for age, gender, body mass index, HbA1c, smoking, energy intake, and other confounders. Mean vitamin B6 intake in quartiles ranged from 0.9 to 2.0 mg/day and half of participants had vitamin B6 intake less than the recommended dietary allowance according to dietary reference intakes in Japan (males 1.4 mg/day; females 1.2 mg/day). Patients in higher quartiles included those with significantly high energy, vegetable, meat and fish intakes (p for trend< 0.01, < 0.01, < 0.01, and < 0.01, respectively). After adjusting for confounders, hazard ratios for diabetic retinopathy in the 2nd, 3rd, and 4th quartiles of vitamin B6 intake compared with the 1st quartile were 1.2 (95% confidence interval 0.8-1.7, p=0.36), 0.9 (0.6-1.3, p=0.51), and 0.51 (0.31-0.88, p=0.01), respectively. We clarified that the decreased incidence of diabetic retinopathy in Japanese patients with type 2 diabetes was associated with high vitamin B6 intake.
C. Horikawa: None. R. Aida: None. S. Tanaka: None. Y. Yoshimura: None. R. Kawasaki: None. T. Moriya: None. A. Araki: None. H. Sone: Research Support; Self; Novo Nordisk Inc., Eli Lilly and Company, MSD K.K., Chugai Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Development Center Asia, Pte. Ltd., Daiichi Sankyo Company, Limited, Ono Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd., Sanofi, Kowa Pharmaceuticals America, Inc., Eisai Inc..