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.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1464-5491.2007.02360.x

Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels.

Background:Low vitamin D status has been suggested as a risk factor for type 2 diabetes. Although the epidemiologic evidence is scarce, 2 recent studies have suggested an association. The present study investigated the relation of serum vitamin D with type 2 diabetes incidence using pooled data from

Serum vitamin D and subsequent occurrence of type 2 diabetes.

http://media.journals.elsevier.com/content/files/s1568997212001310-10080459.pdf

Can supplementation with vitamin D reduce the risk or modify the course of autoimmune diseases? A systematic review of the literature.

https://link.springer.com/content/pdf/10.1007%2Fs00125-005-1802-7.pdf

Vitamin D and Diabetes

Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome.

We report data from a pilot study examining vitamin D deficiency in type 1 and type 2 diabetes. Serum 25-OH vitamin D (25-OH-D) levels were measured in type 1 ( n = 50) and type 2 diabetic ( n = 63) individuals at the time of their routine visits for diabetes management. Patients had no prior history of metabolic bone disease, vitamin D deficiency, parathyroid disease, malabsorption, or significant elevations of serum creatinine or liver enzymes. Most subjects (74.3%) were prescribed a daily multivitamin as part of their routine diabetes care, but none were taking additional supplements. Serum was obtained during “light” (April to September) and “dark” (October to March) months. Serum 25-OH-D levels were …

https://care.diabetesjournals.org/content/diacare/29/1/174.1.full.pdf

David J. Di Cesar

Papers

Vitamin D Deficiency Is More Common in Type 2 Than in Type 1 Diabetes