title: EFFECT OF HIGH-DOSE VITAMIN D REPLETION ON GLYCEMIC CONTROL IN AFRICAN-AMERICAN MALES WITH PREDIABETES AND HYPOVITAMINOSIS D.
abstract: OBJECTIVE
  This double-blind, randomized, controlled trial evaluated whether 12 months of high-dose vitamin D2 supplementation improved insulin sensitivity and secretion and glycemic status.
  
  
  METHODS
  African-American males (AAM) with prediabetes (glycosylated hemoglobin [A1C] 5.7-6.4%), hypovitaminosis D (25-hydroxyvitamin D [25OHD] 5-29 ng/mL), and prevalent medical problems were supplemented with vitamin D3 (400 IU/day) and then randomized to weekly placebo or vitamin D2 (50,000 IU). The primary outcome was the change in oral glucose insulin sensitivity (OGIS, from an oral glucose tolerance test [OGTT]) after 12 months of treatment. Secondary outcomes included other glycemic indices, A1C, and incident diabetes.
  
  
  RESULTS
  Baseline characteristics were similar in vitamin D-supplemented (n = 87) and placebo (n = 86) subjects completing the trial with average concentrations 14.4 ng/mL, 362 mL × min(-1) × m(-2), and 6.1% for 25OHD, OGIS and A1C, respectively. After 12 months, the vitamin D-supplemented group had a change in serum 25OHD +35 versus +6 ng/mL for placebo, P<.001; OGIS +7.8 versus -16.0 mL × min(-1) × m(-2) for placebo, P = .026; and A1C -0.01 versus +0.01% for placebo, P = .66. Ten percent of subjects in both groups progressed to diabetes. A posthoc analysis of participants with baseline impaired fasting glucose (IFG) showed that more subjects in the vitamin D subgroup (31.6%) than placebo (8.3%) returned to normal glucose tolerance, but the difference did not reach significance (P = .13).
  
  
  CONCLUSIONS
  The trial does not provide evidence that 12 months of high-dose D2 repletion improves clinically relevant glycemic outcomes in subjects with prediabetes and hypovitaminosis D (NCT01375660).
authors.forename: Elena
authors.initials: E
authors.lastname: Barengolts
authors.forename: Buvana
authors.initials: B
authors.lastname: Manickam
authors.forename: Yuval
authors.initials: Y
authors.lastname: Eisenberg
authors.forename: Arfana
authors.initials: A
authors.lastname: Akbar
authors.forename: Subhash
authors.initials: S
authors.lastname: Kukreja
authors.forename: Irina
authors.initials: I
authors.lastname: Ciubotaru
mesh_terms: D001741:Black or African American; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D019587:Dietary Supplements; D004311:Double-Blind Method; D004872:Ergocalciferols / Q000008:administration & dosage*; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood / Q000188:drug therapy*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000188:drug therapy*
chemical_list: D001786:Blood Glucose; D004872:Ergocalciferols; D006442:Glycated Hemoglobin; D014807:Vitamin D; C517652:hemoglobin A1c protein, human; C104450:25-hydroxyvitamin D