title: Vitamin D deficiency increases the risk of retinopathy in Chinese patients with type 2 diabetes.
abstract: OBJECTIVE
  To investigate the relationship between vitamin D deficiency and diabetic retinopathy.
  
  
  METHODS
  In total, 1520 patients with Type 2 diabetes were recruited and divided into three groups according to their fundus oculi results: no diabetic retinopathy (n = 625, 41.12%); non-sight-threatening diabetic retinopathy (n = 562, 36.97%); and sight-threatening diabetic retinopathy (n = 333, 21.91%). Vitamin D deficiency was defined as a serum circulating 25-hydroxyvitamin D level < 20 ng/ml. Clinical characteristics and biochemical parameters were detected and compared.
  
  
  RESULTS
  The patients with sight-threatening diabetic retinopathy had significantly lower serum 25-hydroxyvitamin D concentrations and higher prevalence of vitamin D deficiency than other two groups (all P < 0.05). In addition, there was a downward trend in average 25-hydroxyvitamin D level with the increased stages of diabetic retinopathy (P < 0.01). The prevalence of diabetic retinopathy and sight-threatening diabetic retinopathy in patients with vitamin D deficiency was also higher than in those without vitamin D deficiency (both P < 0.01). After adjusting for all potential confounders, vitamin D deficiency was still associated with increased risk of diabetic retinopathy (odds ratio 1.93) and sight-threatening diabetic retinopathy (odds ratio 2.42) (both P < 0.01). Logistical regression analysis further revealed that vitamin D deficiency was an independent risk factor for diabetic retinopathy (β = 0.66) and sight-threatening diabetic retinopathy (β = 0.93) (both P < 0.01). ROC analysis indicated that a serum 25-hydroxyvitamin D level < 15.57 ng/ml suggested the occurrence of sight-threatening diabetic retinopathy (odds ratio 2.38, P < 0.01).
  
  
  CONCLUSIONS
  Vitamin D deficiency is an independent risk factor for diabetic retinopathy and sight-threatening diabetic retinopathy. The prevalence of sight-threatening diabetic retinopathy doubles when the serum 25-hydroxyvitamin D level is < 15.57 ng/ml.
authors.affiliation: Department of Endocrinology and Metabolism.
authors.forename: R
authors.initials: R
authors.lastname: He
authors.forename: J
authors.initials: J
authors.lastname: Shen
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.forename: H
authors.initials: H
authors.lastname: Zeng
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Yu
authors.forename: H
authors.initials: H
authors.lastname: Lu
authors.forename: F
authors.initials: F
authors.lastname: Lu
authors.forename: Q
authors.initials: Q
authors.lastname: Wu
authors.forename: W
authors.initials: W
authors.lastname: Jia
mesh_terms: D000368:Aged; D002681:China / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D003930:Diabetic Retinopathy / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D