title: A randomised controlled trial evaluating the impact of targeted vitamin D supplementation on endothelial function in type 2 diabetes mellitus: The DIMENSION trial.
abstract: We sought to determine if vitamin D supplementation, to target 25(OH)D concentrations of 30-40 ng/mL, improves endothelial function in Singapore's multi-ethnic type 2 diabetes mellitus population. We randomised 64 type 2 diabetes mellitus patients with hypovitaminosis D to cholecalciferol 4000 International Unit/matching placebo [baseline 25(OH)D < 20 ng/mL] or cholecalciferol 2000 International Unit/matching placebo [baseline 25(OH)D: 20-30 ng/mL] daily for 16 weeks with a down titration at 8 weeks if 25(OH)D > 30 ng/mL. Endothelial function was assessed by peripheral tonometry (reactive hyperaemia index-endothelial peripheral arterial tonometry) and vascular biomarkers: E-selectin, von-Willebrand factor and high-sensitivity C-reactive protein. We compared the change from baseline parameters in the two groups using Student's t-test or Kruskal-Wallis test. A log-normal multivariate regression analysis was used to adjust for relevant baseline variables. The median reactive hyperaemia index in the vitamin D group increased from 0.65 (interquartile range: 0.42) to 0.73 (interquartile range: 0.36), whereas it decreased from 0.73 (interquartile range: 0.65) to 0.65 (interquartile range: 0.38) (p = 0.02) in the placebo group. After adjustment for baseline variables, the change was not statistically significant for reactive hyperaemia index (p = 0.07) and for other vascular biomarkers (p > 0.05). Targeted vitamin D supplementation for 16 weeks resulted in a small but non-significant improvement in endothelial function in a type 2 diabetes mellitus cohort.
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore Yong Loo Lin School of Medicine, National University of Singapore, Singapore DUKE-NUS Medical School, National University of Singapore, Singapore Metabolic Medicine Research Program, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore rinkoo_dalan@ttsh.com.sg.
authors.forename: Rinkoo
authors.initials: R
authors.lastname: Dalan
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore.
authors.forename: Huiling
authors.initials: H
authors.lastname: Liew
authors.affiliation: Department of Biostatistics, Singapore Clinical Research Institute, Singapore Centre for Quantitative Medicine, Duke-NUS Graduate Medical School, National University of Singapore, Singapore.
authors.forename: Pryseley Nkouibert
authors.initials: PN
authors.lastname: Assam
authors.affiliation: Department of Biostatistics, Singapore Clinical Research Institute, Singapore Centre for Quantitative Medicine, Duke-NUS Graduate Medical School, National University of Singapore, Singapore.
authors.forename: Edwin Sy
authors.initials: ES
authors.lastname: Chan
authors.affiliation: Department of Biostatistics, Singapore Clinical Research Institute, Singapore Centre for Quantitative Medicine, Duke-NUS Graduate Medical School, National University of Singapore, Singapore.
authors.forename: Fahad Javaid
authors.initials: FJ
authors.lastname: Siddiqui
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore.
authors.forename: Alvin Wk
authors.initials: AW
authors.lastname: Tan
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore.
authors.forename: Daniel Ek
authors.initials: DE
authors.lastname: Chew
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore Metabolic Medicine Research Program, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore Imperial College London, London, UK.
authors.forename: Bernhard O
authors.initials: BO
authors.lastname: Boehm
authors.affiliation: Department of Endocrinology, Tan Tock Seng Hospital, Singapore Singapore Institute for Clinical Sciences, A*STAR, Singapore National Healthcare Group, Singapore.
authors.forename: Melvin Ks
authors.initials: MK
authors.lastname: Leow
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002762:Cholecalciferol / Q000009:adverse effects / Q000627:therapeutic use*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000175:diagnosis; D003925:Diabetic Angiopathies / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012846:Singapore; D062606:Tertiary Care Centers; D013997:Time Factors; D016896:Treatment Outcome; D014664:Vasodilation / Q000187:drug effects*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D
keywords: Vitamin D; cholecalciferol; endothelial function; type 2 diabetes
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