Phase 3
N=22,220
Study of Vitamin D and Omega-3 Supplementation for Preventing Diabetes
Type 2 Diabetes
Bottom Line
View on ClinicalTrials.gov: NCT01633177 ↗Enrolled (actual)
22,220
Serious AEs
12.0%
Results posted
Apr 2026
Primary outcome: Primary: Incident Type 2 Diabetes — 121; 109; 139; 115 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 3
- Interventions
- Vitamin D3 (Dietary_supplement); Omega-3 fatty acid (fish oil) (Drug); Vitamin D3 placebo (Dietary_supplement); Fish oil placebo (Drug)
- Age
- Adult, Older Adult · 50+ yrs
- Sex
- All
- Sponsor
- Brigham and Women's Hospital
- Primary completion
- May 2024
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Incident Type 2 Diabetes |
121; 109; 139; 115 | — |
| SECONDARY OGTT Index of Insulin Sensitivity |
-3.3; -3.5; -5.2; -3.0 | — |
| SECONDARY OGTT Index of Beta-cell Function |
-0.8; -2.3; 2.7; -1.7 | — |
| SECONDARY HbA1c Levels |
0.2; 0.5; 0.2; 0.5 | — |
Summary
The VITamin D and OmegA-3 TriaL (VITAL; NCT 01169259) is an ongoing randomized clinical trial in 25,875 U.S. men and women investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor® fish oil, 1 gram) reduces the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This ancillary study is being conducted among nondiabetic participants in VITAL and will examine whether vitamin D or fish oil prevent type 2 diabetes. Findings from this ancillary study (n=22220 without diabetes at baseline) conducted within the VITAL trial will clarify whether vitamin D and omega-3 fatty acid supplementation reduces risk of type 2 diabetes and thus will inform public health and clinical guidelines for diabetes prevention.
Eligibility Criteria
Participants in VITAL (NCT01169259) who have no history of diabetes mellitus at baseline are eligible to participate in this ancillary study.
Data sourced from ClinicalTrials.gov (NCT01633177). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.