Effect of Vitamin D3 Supplementation on Insulin Resistance- The DIR Study
Insulin resistance is a state where the body does not respond as it should to the insulin it produces. Individuals who are insulin resistant are at increased risk of both heart disease and type 2 diabetes; importantly, diabetes more than doubles the risk of heart disease, independent of other recognised risk factors. Interventions that prevent or reverse insulin resistance may help to attenuate risk of heart disease and diabetes. A number of randomised controlled trials provide proof of concept evidence regarding a beneficial effect of vitamin D on insulin resistance and other cardiovascular risk markers but experts have stated that further studies are required. Importantly, these studies should use appropriate endpoints, provide a high enough dose of vitamin D to optimise vitamin D status, and they should be conducted in clearly defined populations, The vitamin D trial we propose addresses these issues and aims to evaluate a potentially straightforward and low cost health care intervention for populations at highrisk of heart disease and diabetes. Specifically, this study would provide clinically relevant information on the metabolic effects of optimising vitamin D status in these high risk patients. This has clear economic and social implications given the current, and projected, burden of heart disease and diabetes.
This study will investigate the effect of vitamin D3 supplementation on insulin resistance and cardiovascular risk factors in people at high risk of type 2 diabetes and cardiovascular disease using the gold standard euglycaemic hyperinsulinaemic clamp method.
Sub-optimal Vitamin D Status
Dietary Supplement: Vitamin D3 supplementation
|Study Design:||Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
|Official Title:||Effect of Vitamin D3 Supplementation on Insulin Resistance and Cardiovascular Risk Factors in People at High Risk of Type 2 Diabetes and Cardiovascular Disease (The DIR Study)|
- Change in Insulin Resistance [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]Insulin resistance will be measured using the gold standard euglycaemic-hyperinsulinaemic clamp method (note - it is anticipated that a total of 60 volunteers will complete the primary endpoint assessment).
- Change in vitamin D status [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]Change in vitamin D status will be measured using the gold standard Ultra performance liquid chromatography followed by tandem mass spectrometry
- Change in markers of cardiovascular risk [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]Measurements of seated and 24-hour ambulatory blood pressure, lipids, homeostasis model assessment (HOMA), HbA1c, and inflammatory and immune function markers including tumour necrosis factor-alpha and high sensitivity c-reactive protein
- Change in carotid-femoral pulse wave velocity (PWV) [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]Assessed by sequential tonometry with ECG gating using the SphygmoCor PWV System
- Change in hand grip strength [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]Assessed using hand held dynamometer
- Health status [ Time Frame: Measured at baseline and after 6 months ] [ Designated as safety issue: No ]SF-36 Questionnaire
|Study Start Date:||August 2013|
|Estimated Study Completion Date:||December 2016|
|Estimated Primary Completion Date:||December 2016 (Final data collection date for primary outcome measure)|
Active Comparator: Vitamin D3 supplementation
Patients will take 3000IU (75 µg) Vitamin D3 supplementation per day for a period of 26 weeks.
Dietary Supplement: Vitamin D3 supplementation
3000IU (75µg) vitamin D3 will be given daily for a period of 26 weeks to the group who receive the active comparator. The efficacy of vitamin D3 supplementation on insulin resistance will be compared to the placebo group.
Placebo Comparator: Placebo
Please refer to this study by its ClinicalTrials.gov identifier: NCT01889810
|Contact: Michelle McKinley, PhDfirstname.lastname@example.org|
|Contact: Steven J Hunter, MDemail@example.com|
|Queen's University, Belfast||Recruiting|
|Belfast, N. Ireland, United Kingdom, BT12 6BJ|
|Contact: Michelle McKinley, PhD 02890632685 firstname.lastname@example.org|
|Contact: Steven J Hunter, MD 02890471883 email@example.com|
|Sub-Investigator: Steven J Hunter, MD|
|Principal Investigator: Michelle McKinley, PhD|
|Sub-Investigator: Ian Young, MD|
|Sub-Investigator: Helen J Wallace, MB|
|Sub-Investigator: Lauren Holmes, BSc(Hons)|
|Principal Investigator:||Michelle McKinley, PhD||Queen's University, Belfast|