Vitamin D supplementation and prevention of Type 2 diabetes.

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The New England journal of medicine.

MeSH Headings

Administration, Oral, Aged, Cholecalciferol, Diabetes Mellitus, Type 2, Dietary Supplements, Disease-Free Survival, Double-Blind Method, Female, Humans, Kaplan-Meier Estimate, Male, Middle Aged, Prediabetic State, Risk Factors, Treatment Failure, Vitamin D, Vitamins


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.

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

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 (95% confidence interval, 0.75 to 1.04; P = 0.12). The incidence of adverse events did not differ significantly between the two groups.

CONCLUSIONS: Among persons at high risk for type 2 diabetes not selected for vitamin D insufficiency, vitamin D



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