Abstract 14289: The Effect of Vitamin D Supplementation on Cardiovascular Risk in Patients With Prediabetes in the D2d Study

Introduction: Low blood 25(OH)D levels are associated with increased cardiovascular (CVD) risk; however; it is unknown whether vitamin D supplementation reduces CVD risk or CVD events. In a secondary analysis from the D2d study, a large diabetes prevention trial, we investigated effects of vitamin D on CVD outcomes. Methods: Persons with prediabetes (n=2,423) not selected for vitamin D insufficiency were randomized to 4000 IU/day of vitamin D 3 or placebo and followed for a median duration of 2.5 years. The primary outcome for this analysis was first occurrence during the study of a composite 4-point Major Adverse Cardiovascular Events (MACE). Secondary aims evaluated effects on expanded MACE (MACE + revascularization) and on CVD risk variables (BP, lipids, CRP and Atherosclerotic Cardiovascular Disease score). All CVD events were independently adjudicated. In ITT analyses, Cox proportional models compared hazard rates between the two groups on 4-point and expanded MACE. Results: Baseline characteristics included 49% women, mean age was 60 years old, and 13% had established CVD by history. There were no significant differences in key baseline characteristics between the two groups. By month 24, the mean serum 25(OHD) 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). A primary MACE event occurred in 21 versus 12 subjects in the vitamin D versus placebo group (Hazard ratio 1.81, 95%CI 0.89-3.69). The number of expanded MACE events were the same between the two groups (n=27 in each group, hazard ratio 1.02, 95%CI, 0.59-1.76). CVD risk variables did not change significantly with vitamin D versus placebo. Conclusion: In a pre-diabetes population not selected for vitamin D insufficiency, vitamin D supplementation did not lower CVD risk.