title: The effect of high-dose vitamin D supplementation on insulin resistance and arterial stiffness in patients with type 2 diabetes.
abstract: OBJECTIVE
  Recent epidemiological studies revealed a striking inverse relationship between vitamin D levels, glucose intolerance/insulin resistance (IR), and cardiovascular disease. However, few interventional studies have evaluated the effect of vitamin D supplementation on cardiovascular risk, such as IR and arterial stiffness, in diabetes. We investigated the role of vitamin D supplementation on cardiovascular risk in type 2 diabetes patients, including metabolic parameters, IR, and arterial stiffness.
  
  
  METHODS
  We enrolled patients who were taking antidiabetic medications or managed their diabetes using lifestyle changes. We excluded patients who were taking vitamin D or calcium supplements. We randomized participants into the vitamin D group (cholecalciferol 2,000 IU/day + calcium 200 mg/day, n = 40) or the placebo group (calcium 200 mg/day, n = 41). We compared their IR (homeostasis model of assessment [HOMA]-IR) and arterial stiffness (brachial-ankle pulse wave velocity and radial augmentation index) before and after 24 weeks of intervention.
  
  
  RESULTS
  The baseline characteristics of the two groups were similar. A total of 62 participants (placebo, 30; vitamin D, 32) completed the study protocol. At the end of the study period, the 25-hydroxyvitamin D [25(OH)D] levels were significantly higher in the vitamin D group than in the placebo group (35.4 ± 8.5 ng/mL vs. 18.4 ± 7.3 ng/mL, p < 0.001). There was no difference in HOMA-IR or changes in arterial stiffness (placebo, 21, vitamin D, 24) between the groups.
  
  
  CONCLUSIONS
  Our data suggest that high-dose vitamin D supplementation might be effective in terms of elevating 25(OH)D levels. However, we identified no beneficial effects on cardiovascular risk in type 2 diabetes, including IR and arterial stiffness.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors.forename: Ohk-Hyun
authors.initials: OH
authors.lastname: Ryu
authors.affiliation: Department of Healthcare Management, Hallym University School of Business, Chuncheon, Korea.
authors.forename: Wankyo
authors.initials: W
authors.lastname: Chung
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors.forename: Sungwha
authors.initials: S
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors.forename: Kyung-Soon
authors.initials: KS
authors.lastname: Hong
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors.forename: Moon-Gi
authors.initials: MG
authors.lastname: Choi
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Hallym University College of Medicine, Chuncheon, Korea.
authors.forename: Hyung Joon
authors.initials: HJ
authors.lastname: Yoo
mesh_terms: D002136:Calcium, Dietary / Q000008:administration & dosage; D002762:Cholecalciferol / Q000008:administration & dosage*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D059289:Vascular Stiffness / Q000187:drug effects*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000188:drug therapy
chemical_list: D002136:Calcium, Dietary; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D
keywords: Diabetes mellitus, type 2; Insulin resistance; Vascular stiffness; Vitamin D deficiency