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 glycemicstatus. Methods: African-American males (AAM) with prediabetes(glycosylated hemoglobin [A1C] 5.7–6.4%), hypovitaminosisD (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 glycemicindices, 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 g...