title: Effect of vitamin D replacement on indexes of insulin resistance in overweight elderly individuals: a randomized controlled trial.
abstract: BACKGROUND
  It is unclear whether and at what dose vitamin D supplementation affects insulin resistance (IR).
  
  
  OBJECTIVE
  We sought to investigate whether vitamin D at doses higher than currently recommended decreases indexes of IR in an ambulatory population of overweight elderly subjects.
  
  
  METHODS
  This double-blind, randomized, controlled multicenter trial enrolled 257 elderly overweight individuals aged ≥65 y with baseline 25-hydroxyvitamin D [25(OH)D] concentrations between 10 and 30 ng/mL. All subjects received 1000 mg calcium citrate/d, with vitamin D administered weekly at an equivalent dose of 600 or 3750 IU/d. The homeostasis model assessment (HOMA) of IR index at 1 y was the primary outcome. We also assessed the McAuley index.
  
  
  RESULTS
  In total, 222 subjects (55% women) with a mean ± SD age and body mass index (BMI; in kg/m(2)) of 71 ± 4 y and 30 ± 4, respectively, completed the study. Subjects' baseline characteristics, including IR indexes, were similar across groups: 69% had prediabetes, 54% had hypertension (47% were taking antihypertensive medications), and 60% had hyperlipidemia, nearly half of whom were receiving lipid-lowering drugs. At 1 y, mean ± SD serum 25(OH)D increased from 20 ± 7 to 26 ± 7 ng/mL in the low-dose arm (P < 0.0001) and from 21 ± 8 to 36 ± 10 ng/mL in the high-dose arm (P < 0.001). Median HOMA-IR indexes did not change compared with baseline concentrations and were similar in the high- [2.2 (IQR: 1.5, 2.9)] and low-dose [2.3 (IQR: 1.6, 3.3] treatment groups. Adjusted analyses showed that HOMA-IR was predicted by the baseline HOMA index and BMI but not by vitamin D dose, baseline serum 25(OH)D, or change in 25(OH)D.
  
  
  CONCLUSIONS
  Vitamin D3 at 3750 IU/d did not improve HOMA-IR compared with the Institute of Medicine Recommended Dietary Allowance of 600 IU/d in elderly overweight individuals. This trial was registered at clinicaltrials.gov as NCT01315366.
authors.affiliation: Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon; gf01@aub.edu.lb.
authors.forename: Ghada
authors.identifier: http://orcid.org/0000-0002-2076-5858
authors.initials: G
authors.lastname: El-Hajj Fuleihan
authors.affiliation: Departments of Rheumatology and.
authors.forename: Rafic
authors.initials: R
authors.lastname: Baddoura
authors.affiliation: Departments of Internal Medicine and.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Habib
authors.affiliation: Endocrinology, Hȏtel-Dieu de France, Beirut, Lebanon;
authors.forename: Georges
authors.initials: G
authors.lastname: Halaby
authors.affiliation: Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon;
authors.forename: Asma
authors.initials: A
authors.lastname: Arabi
authors.affiliation: Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon;
authors.forename: Maya
authors.initials: M
authors.lastname: Rahme
authors.affiliation: Division of Clinical Biochemistry and Immunology, Mayo Clinic, Rochester, MN;
authors.forename: Ravinder J
authors.initials: RJ
authors.lastname: Singh
authors.affiliation: Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark; and.
authors.forename: Moustapha
authors.initials: M
authors.lastname: Kassem
authors.affiliation: Department of Health Policy and Research, Weill Cornell Medical College, Doha, Qatar.
authors.forename: Ziyad
authors.initials: Z
authors.lastname: Mahfoud
authors.affiliation: Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon;
authors.forename: Maha
authors.initials: M
authors.lastname: Hoteit
authors.affiliation: Pathology and Laboratory Medicine and.
authors.forename: Rose T
authors.initials: RT
authors.lastname: Daher
authors.affiliation: Division of Endocrinology, Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon;
authors.forename: Mohamed-Faisal
authors.initials: MF
authors.lastname: Kassir
mesh_terms: D000368:Aged; D015992:Body Mass Index; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D015897:Comorbidity; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D009765:Obesity / Q000097:blood / Q000150:complications; D050177:Overweight; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use
chemical_list: D014815:Vitamins; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D
keywords: HOMA; IOM RDA; high-dose vitamin D; insulin resistance; prediabetes