Citation: New England Journal of Medicine. 2019 Jun 07.Journal: The New England journal of medicine.Published: ; 2019ISSN: 0028-4793.Full author list: Pittas AG; Dawson-Hughes B; Sheehan P; Ware JH; Knowler WC; Aroda VR; Brodsky I; Ceglia L; Chadha C; Chatterjee R; Desouza C; Dolor R; Foreyt J; Fuss P; Ghazi A; Hsia DS; Johnson KC; Kashyap SR; Kim S; LeBlanc ES; Lewis MR; Liao E; Neff LM; Nelson J; O'Neil P; Park J; Peters A; Phillips LS; Pratley R; Raskin P; Rasouli N; Robbins D; Rosen C; Vickery EM; Staten M; D2d Research Group.UI/PMID: 31173679.Subject(s): IN PROCESS -- NOT YET INDEXEDInstitution(s): MedStar Good Samaritan Hospital | MedStar Health Research InstituteActivity type: Journal Article.Medline article type(s): Journal ArticleOnline resources: Click here to access onlineDigital Object Identifier: https://dx.doi.org/10.1056/NEJMoa1900906 (Click here)Abbreviated citation: N Engl J Med. 2019 Jun 07.Local Holdings: Available online from MWHC library: 1993 - present, Available in print through MWHC library: 1980 - present.Abstract: BACKGROUND: Observational studies support an association between a low blood 25-hydroxyvitamin D level and the risk of type 2 diabetes. However, whether vitamin D supplementation lowers the risk of diabetes is unknown.Abstract: METHODS: We randomly assigned adults who met at least two of three glycemic criteria for prediabetes (fasting plasma glucose level, 100 to 125 mg per deciliter; plasma glucose level 2 hours after a 75-g oral glucose load, 140 to 199 mg per deciliter; and glycated hemoglobin level, 5.7 to 6.4%) and no diagnostic criteria for diabetes to receive 4000 IU per day of vitamin D<sub>3</sub> or placebo, regardless of the baseline serum 25-hydroxyvitamin D level. The primary outcome in this time-to-event analysis was new-onset diabetes, and the trial design was event-driven, with a target number of diabetes events of 508.Abstract: RESULTS: A total of 2423 participants underwent randomization (1211 to the vitamin D group and 1212 to the placebo group). By month 24, the mean serum 25-hydroxyvitamin D level in the vitamin D group was 54.3 ng per milliliter (from 27.7 ng per milliliter at baseline), as compared with 28.8 ng per milliliter in the placebo group (from 28.2 ng per milliliter at baseline). After a median follow-up of 2.5 years, the primary outcome of diabetes occurred in 293 participants in the vitamin D group and 323 in the placebo group (9.39 and 10.66 events per 100 person-years, respectively). The hazard ratio for vitamin D as compared with placebo was 0.88 (0.95% confidence interval, 0.75 to 1.04; P = 0.12). The incidence of adverse events did not differ significantly between the two groups.Abstract: CONCLUSIONS: Among persons at high risk for type 2 diabetes not selected for vitamin D insufficiency, vitamin D<sub>3</sub> supplementation at a dose of 4000 IU per day did not result in a significantly lower risk of diabetes than placebo. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; D2d ClinicalTrials.gov number, NCT01942694.).Abstract: Copyright (c) 2019 Massachusetts Medical Society.