Clinical Trial Details
— Status: Active, not recruiting
Administrative data
| NCT number |
NCT01633177 |
| Other study ID # |
0308112690000 |
| Secondary ID |
R01DK088078 |
| Status |
Active, not recruiting |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
September 2010 |
| Est. completion date |
May 30, 2024 |
Study information
| Verified date |
May 2023 |
| Source |
Brigham and Women's Hospital |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial 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 proposed study 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.
Description:
Emerging evidence suggests favorable effects of both vitamin D and marine omega-3 fatty acids
on glucose homeostasis. Optimal vitamin D intake is essential for insulin secretion and
action, and omega-3 fatty acids may reduce diabetes risk as a result of favorable effects on
insulin sensitivity, endothelial function, chronic inflammation, or other metabolic
abnormalities. Although the metabolic effects of vitamin D and omega-3 fatty acids show
considerable promise for the primary prevention of type 2 diabetes (T2D), there are no
completed, ongoing, or planned randomized clinical trials of vitamin D or omega-3 supplements
that include T2D as a primary outcome in a general population.
We thus propose to utilize an NIH-funded randomized trial (1 U01 CA138962) to test the
hypothesis that vitamin D and omega-3 supplementation will reduce the risk of T2D. We will
further assess whether and to what extent vitamin D or omega-3 supplementation will improve
insulin sensitivity and pancreatic beta-cell function in a subsample of the trial cohort. The
VITamin D and OmegA-3 TriaL (VITAL) is a randomized, double-blind, placebo-controlled trial
specifically designed to evaluate the benefits and risks of vitamin D3 (2,000 IU/day) and
marine omega-3 fatty acid (eicosapentaenoic acid [EPA] + docosahexaenoic acid [DHA], 1g/day)
supplements in the primary prevention of cancer and cardiovascular disease (CVD). The VITAL
trial will aim to enroll 20,000 men and women (aged ≥50 and ≥55 years, respectively). The
planned treatment duration is 5 years after a 1.5-year recruitment period. This diabetes
ancillary study aims to implement an inexpensive and efficient strategy to validate
self-reported incident T2D cases in the entire trial population and to collect pre- and
post-intervention measures of glucose, insulin, and hemoglobin A1c (HbA1c) in a subset of
participants. Two methods of diabetes case validation are proposed. First, we plan to collect
detailed information about diagnostic glucose testing and anti-diabetic medication use from
medical records and/or supplementary questionnaires completed by the participant's physician.
Second, to complement our diabetes ascertainment process, we will also plan to retrieve
additional data on diabetes diagnoses and hypoglycemic medications by linking the
participants with the Centers for Medicare and Medicaid Services (CMS) database. In addition
to evaluating whether the study interventions impact the onset of clinical diabetes, we
propose to collect pre- and post-intervention measures of glucose, insulin, and HbA1c in a
subset of the participants to reliably assess whether vitamin D or omega-3 supplementation
alters insulin and glucose homeostasis. We plan to recruit 1,000 participants without prior
clinical diabetes at the Clinical and Translational Science Center (CTSC) site at Brigham and
Women's Hospital. A standard 2-hour oral glucose tolerance test (OGTT) and HbA1c measurements
will be performed during the CTSC visits at baseline and at 2-year post-randomization.
Primary Aims:
1. To test whether vitamin D3 and/or EPA+DHA supplementation reduces the risk of T2D among
all initially non-diabetic participants in the VITAL trial.
2. To test whether vitamin D3 and/or EPA+DHA supplementation improves insulin sensitivity
and beta-cell function in a subset of 1,000 non-diabetic participants receiving OGTT at
baseline and 2-year post-randomization.
Secondary Aims:
1. To test whether vitamin D3 and/or EPA+DHA supplementation lowers HbA1c, fasting glucose
and insulin, as well as other surrogate indices of insulin sensitivity and beta-cell
function as determined by the homeostasis model assessment (HOMA-IR and HOMA-%B,
respectively) in our substudy.
2. To test whether vitamin D3 and EPA+DHA supplementation exerts synergistic or additive
effects on the risk of T2D among all initially non-diabetic participants in the VITAL
trial.
3. To test whether vitamin D3 and EPA+DHA supplementation exerts synergistic or additive
effects on insulin sensitivity and beta-cell function as assessed by OGTT in our
substudy.
For the above main effect estimates, we will further explore whether the effect of vitamin D3
or EPA+DHA supplementation varies by (1) age, (2) sex, (3) baseline intakes of these
nutrients, (4) baseline levels of 25(OH)D (for vitamin D3), (5) race/skin pigmentation (for
vitamin D3), (6) geographic region (for vitamin D3), and (7) BMI (for vitamin D3).
