MRC Epidemiology Unit- Aims of the study
- Design
- Principal investigators
- Status
- Unit role
- Sponsors
- Partners and stakeholders
- Funding
- Data sharing
- Trial Registration Number
Aims of the study
- To determine whether short-term oral supplementation over four months of vitamin D can lead to a reduction in blood markers of diabetes risk and improvement in markers of cardiovascular risk in people at risk of developing type 2 diabetes. Specifically we aimed to test two types of vitamin D, in the form of vitamin D2 and vitamin D3.
- To examine the feasibility and safety of relatively high dose vitamin D supplementation among individuals from the general population without prior knowledge of their blood vitamin D status.
Design
We designed a double-blind, placebo-controlled randomised clinical trial in people at risk of developing type 2 diabetes, across two sites: East London and Cambridge. We randomly allocated 340 participants to one of three groups who received a monthly oral dose for four months of 100,000 IU (equivalent to 2.5mg) of either ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) or a monthly oral dose of placebo. Each participant was followed up for a total of 4months from their first visit. The first three doses were given at the clinic visit, while the final dose was taken at home after contact by the study team, and their consumption status of the trial investigational medicinal product (IMP) was recorded as complete, partial or failed.
The trial endpoints were assessed at 16 weeks after the last (fourth) dose of the IMP.
Primary outcome
The primary outcome of the trial was a change in the HbA1c concentration (a marker of the glucose status of the body).
Secondary outcomes
There were multiple secondary outcomes, including: systolic and diastolic blood pressure, blood cholesterol, HDL cholesterol, apolipoprotein (Apo)A1 and ApoB, cardiovascular disease (CVD) risk score, as assessed by the UK Prospective Diabetes Study (UKPDS) risk engine (version 2) and additionally in London only, a measurement of arterial stiffness assessed by pulse wave velocity (PWV). Further secondary outcomes (both sites) included anthropometric measures (such as weight and waist circumference) and serum concentrations of high-sensitivity C-reactive protein (hsCRP – a marker of inflammation), fructosamine and parathyroid hormone (PTH).
Other outcomes included the safety of oral vitamin D without a pre-assessment of vitamin D status and the feasibility and safety of the intervention.
Principal investigators
Cambridge
- Professor Nita Forouhi (Lead Investigator)
- Professor Simon Griffin
London
- Professor Graham Hitman (Chief Investigator)
- Professor Christopher Griffiths
- Professor Adrian Martineau
- Professor Stephen Greenwald
- Dr Barbara Boucher
- Dr Tahseen Chowdhury
- Dr Peter Timms
Status
Recruitment and follow-up completed in 2013. Analyses completed over 2015 to 2019 resulting in four publications.
Unit role
Unit led study for the Cambridge site of the trial, with responsibility for data.
Sponsors
The trial was jointly sponsored by Queen Mary University of London and the Medical Research Council Epidemiology Unit (University of Cambridge).
Partners and Stakeholders
Funding
Trial funding was from a block grant from the NHS Tower Hamlets and from MRC Epidemiology Unit core funding (MC_UP_A100_1003).
Data sharing
Please see our Data Sharing pages.