title: Inverse association between high blood 25-hydroxyvitamin D levels and diabetic retinopathy in a representative Korean population.
abstract: OBJECTIVE
  To investigate the association between 25-hydroxyvitamin D and diabetic retinopathy (DR).
  
  
  METHODS
  A population-based cross-sectional study using a nation-wide, systemically stratified, multistage, clustered sampling method included a total of 18,363 subjects aged ≥ 40 years who participated in the Korean National Health and Nutrition Examination Survey during 2008-2012. All participants participated in standardized interviews, blood 25-hydroxyvitamin D level evaluations, and comprehensive ophthalmic examinations. Seven standard retinal fundus photographs were obtained from both eyes after pupil dilatation. DR was graded according to the modified Airlie House classification system.
  
  
  RESULTS
  The blood 25-hydroxyvitamin D levels were 19.2 ng/mL in men and 17.9 ng/mL in women. After adjusting for potential confounders, including age, sex, diabetes duration, hemoglobin A1c levels, and hypertension, the odds ratios (OR) for any DR and proliferative DR among men decreased significantly in the highest blood 25-hydroxyvitamin D level quintile relative to the lowest quintile (OR, 0.37; 95% confidence interval [CI], 0.18-0.76; P for trend  = 0.004 and OR, 0.15; 95% CI, 0.03-0.83; P for trend  = 0.043).
  
  
  CONCLUSIONS
  This study provides the first epidemiologic findings of the inverse relationships of blood 25-hydroxyvitamin D levels with any DR and proliferative DR only in men. Considering anti-angiogenic and anti-fibrotic action of vitamin D, further studies including longitudinal and interventional analysis are warranted.
authors.affiliation: Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea; Department of Epidemiology and Biostatistics, Harvard School of Public Health, Boston, MA, United States of America.
authors.forename: Donghyun
authors.initials: D
authors.lastname: Jee
authors.affiliation: Department of Biostatistics, Department of Preventive medicine, The College of Medicine, Catholic University of Korea, Seoul, Korea.
authors.forename: Kyung do
authors.initials: Kd
authors.lastname: Han
authors.affiliation: Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Eun Chul
authors.initials: EC
authors.lastname: Kim
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D011379:Prognosis; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D