Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels
Article first published online: 14 FEB 2008
© 2008 The Authors
Volume 25, Issue 3, pages 320–325, March 2008
How to Cite
Sugden, J. A., Davies, J. I., Witham, M. D., Morris, A. D. and Struthers, A. D. (2008), Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels. Diabetic Medicine, 25: 320–325. doi: 10.1111/j.1464-5491.2007.02360.x
- Issue published online: 27 FEB 2008
- Article first published online: 14 FEB 2008
- Accepted 1 October 2007
- blood pressure;
- endothelial function;
- vitamin D
Aims To test whether a single large dose of vitamin D2 can improve endothelial function in patients with Type 2 diabetes mellitus and low serum 25-hydroxyvitamin D levels.
Methods Double-blind, parallel group, placebo-controlled randomized trial. A single dose of 100 000 IU vitamin D2 or placebo was administered to patients with Type 2 diabetes over the winter, when levels of circulating 25-hydroxyvitamin D were likely to be lowest. Patients were enrolled if their baseline 25-hydroxyvitamin D level was < 50 nmol/l. Endothelial function and blood pressure were measured and fasting blood samples were taken at baseline and 8 weeks after administration of vitamin D.
Results Forty-nine per cent of subjects screened had 25-hydroxyvitamin D levels < 50 nmol/l. Thirty-four subjects completed the study, with a mean age of 64 years and a baseline 25-hydroxyvitamin D level of 38.3 nmol/l. Vitamin D supplementation increased 25-hydroxyvitamin D levels by 15.3 nmol/l relative to placebo and significantly improved flow mediated vasodilatation (FMD) of the brachial artery by 2.3%. The improvement in FMD remained significant after adjusting for changes in blood pressure. Vitamin D supplementation significantly decreased systolic blood pressure by 14 mmHg compared with placebo; this did not correlate with change in FMD.
Conclusions Vitamin D insufficiency is common in patients with Type 2 diabetes during winter in Scotland. A single large dose of oral vitamin D2 improves endothelial function in patients with Type 2 diabetes and vitamin D insufficiency.