Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Low levels of vitamin D have been associated with higher blood pressure and a higher risk of heart attack and stroke. These are particular problems for people with diabetes, and it is possible that giving extra vitamin D to people with diabetes who have low vitamin D levels might help to protect against heart attacks and strokes. The aim of this study is to find out whether giving vitamin D can reduce blood pressure, improve measures of blood vessel health, and improve glucose levels in diabetes.

Who can participate?
Patients aged over 18 with type 2 diabetes and low levels of vitamin D

What does the study involve?
Participants' vitamin D levels are tested and if these are low, the health of their blood vessels is assessed by doing an ultrasound scan of their arm before and after blowing up a blood pressure cuff on their arm. Blood samples are also taken to measure a series of substances that vitamin D might affect, and their blood pressure is measured. Participants are then randomly allocated take either a single large dose of vitamin D or a matching dummy (placebo) dose with no vitamin D in it. This dose acts over a period of several weeks. All participants are asked to return to repeat all of the tests 8 weeks after this single dose.

What are the possible benefits and risks of participating?
Vitamin D is a safe treatment that has been used for decades. There is a small risk of increasing calcium levels in the blood, but these levels are monitored and anyone with high levels at the start of the study is not included.

Where is the study run from?
Ninewells Hospital (UK)

When is the study starting and how long is it expected to run for?
October 2005 to June 2006

Who is funding the study?
Diabetes UK

Who is the main contact?
Dr Justine Davies

Trial website

Contact information



Primary contact

Dr Justine Davies


Contact details

Dept of Clinical Pharmacology
Ninewells Hospital
United Kingdom
+44 (0)1382 632180

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Does Vitamin D improve markers of vascular health in type 2 diabetes? A randomised controlled trial


Study hypothesis

That Vitamin D improves endothelial function, pulse wave velocity, insulin sensitivity and markers of renin-angiotensin system activation in type 2 diabetics.

Ethics approval

Tayside (now East of Scotland) Research Ethics committee, 13/09/2005, ref: 05/S1401/125

Study design

Randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Type 2 diabetes mellitus


100,000 units ergocalciferol versus placebo

Added 29/08/2017:
Intervention: 100,000 units oral Ergocalciferol (vitamin D2), given once at baseline
Comparator: Matching placebo, given once at baseline
Total duration of treatment and follow-up: 8 weeks for all treatment arms

Intervention type



Drug names

Primary outcome measure

Current primary outcome measures as of 29/08/2017:
Flow-mediated dilatation of the brachial artery in response to reactive hyperaemia, measured by ultrasound at baseline and 8 weeks

Previous primary outcome measures:
Change in flow mediated dilatation of the brachial artery

Secondary outcome measures

Current secondary outcome measures as of 29/08/2017:
1. 25-hydroxyvitamin D, serum calcium, serum phosphate, parathyroid hormone levels, measured by blood tests at baseline and 8 weeks
2. Glycosylated haemoglobin, insulin sensitivity using HOMA index, measured by blood tests at baseline and 8 weeks
3. Office blood pressure, measured by blood pressure cuff at baseline and 8 weeks
4. Renin and angiotensin levels, measured by blood tests at baseline and 8 weeks

Previous secondary outcome measures:
Pulse wave velocity, homeostasis model assessment (HOMA) index, renin, angiotensin, Vitamin D, parathyroid hormone (PTH)

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Age ≥18 years
2. Vitamin D level <50 nmol/l

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Serum creatinine >200 µmol/l
2. Liver function tests >3 x upper limit of normal
3. Corrected calcium >2.55 mmol/l or <2.15 mmol/l
4. Metastatic malignancy
5. Unable to give informed consent

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Ninewells Hospital
United Kingdom

Sponsor information


University of Dundee (UK)

Sponsor details

11 Perth Road
United Kingdom
+44 (0)1382 344664

Sponsor type




Funder type


Funder name

Diabetes UK

Alternative name(s)

Funding Body Type

private sector organisation

Funding Body Subtype

Other non-profit organizations


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

IPD sharing statement
The datasets generated during and/or analysed during the current study are available upon request from Dr Miles Witham ( Anonymised Individual participant data on all those randomised will be made available to bona fide researchers for non-commercial use, subject to sight of an analysis plan and subject to appropriate data sharing agreements and approval from the trial sponsor.

Intention to publish date

Participant level data

Available on request

Basic results (scientific)

See additional file ISRCTN46424296_BasicResults_18Aug17.pdf

Publication list

2008 results in:

Publication citations

  1. Results

    Sugden JA, Davies JI, Witham MD, Morris AD, Struthers AD, Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels., Diabet. Med., 2008, 25, 3, 320-325, doi: 10.1111/j.1464-5491.2007.02360.x.

Additional files

Editorial Notes

29/08/2017: Ethics approval, interventions and outcome measures details added, plain English summary added. The basic results of this trial have been uploaded as an additional file. 18/08/2017: Recruitment dates and IPD sharing statement added.