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Vitamin D supplementation in patients with diabetes mellitus type 2 on different therapeutic regimens: a one-year prospective study

Khalid M Alkharfy134*, Nasser M Al-Daghri234, Shaun B Sabico23, Abdulaziz Al-Othman5, Osama Moharram6, Majed S Alokail234, Yousef Al-Saleh47, Sudhesh Kumar8 and George P Chrousos39

Author Affiliations

1 Department of Clinical Pharmacy, College of Pharmacy, King Saud University, PO Box 2457, 11451, Riyadh, Saudi Arabia

2 Biochemistry Department, College of Science, King Saud University, PO Box 2455, 11451, Riyadh, Saudi Arabia

3 Biomarkers Research Program, King Saud University, 11451, Riyadh, Saudi Arabia

4 Prince Mutaib Chair for Biomarkers of Osteoporosis, King Saud University, 11451, Riyadh, Saudi Arabia

5 College of Applied Medical Sciences, King Saud University, 11451, Riyadh, Saudi Arabia

6 King Abdulaziz University Hospital, King Saud University, 11451, Riyadh, Saudi Arabia

7 King Abdulaziz Medical City, 11426, Riyadh, Saudi Arabia

8 Division of Metabolic and Vascular Health, Clinical Sciences Research Institute, University Hospitals Coventry and Warwickshire Trust, Walsgrave, CV2 2DX, Coventry, UK

9 First Department of Pediatrics, Athens University Medical School, 11527, Athens, Greece

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Cardiovascular Diabetology 2013, 12:113  doi:10.1186/1475-2840-12-113

Published: 7 August 2013



Little or no research has determined the effect of vitamin D3 supplementation in conjunction with pharmacological and non-pharmacological approaches in the diabetes mellitus type 2 (DMT2) patients. The objective of this study was to determine the effect of vitamin D3 supplementation in a cohort of Saudi DMT2 population on diet, insulin and/or different oral hypoglycemic agents and compare them with a non-DMT2 control cohort.


A total of 499 randomly selected Saudi subjects divided into 8 groups [Non-DMT2 Control = 151; Rosiglitazone alone = 49; Diet = 15; Insulin alone = 55; Insulin + Orals = 12; Metformin alone = 121; Oral agents combination = 37; Sulphonylurea alone = 59] were included in this 12-month interventional study. All DMT2 patients were given 2000 IU vitamin D3 daily, while the control group received none but were advised to increase sun exposure. Anthropometrics, glucose, lipid profile and 25-hydroxyvitamin D (25-OHVitD) were measured at baseline, 6 and 12 months.


Circulating 25-OHVitD concentrations improved in all patient groups. The metformin group showed the highest change in circulating vitamin D levels both at 6 months (62.6%) and 12 months (50.6%) as compared to baseline (p < 0.001). No significant changes were observed in the BMI and glucose in any of the DMT2 groups. In contrast, the insulin + oral agents group showed more significant improvements in the metabolic profile, which included triglycerides and total cholesterol, as well as systolic blood pressure and HDL-cholesterol in males. Also, significant decreases in triglycerides were observed in the rosiglitazone and insulin + oral hypoglycemic agent groups both at 6 and 12 months of supplementation (both p-values <0.001).


While in all DMT2 groups circulating levels of 25-OHVitD increased after supplementation, in DMT2 patients on insulin in combination with other drugs benefitted the most in improving cardiovascular risk. Metformin improves 25-hydroxyvitamin D levels but did not seem to confer other added cardiometabolic benefits.

Vitamin D; Vitamin D supplementation; Diabetes mellitus; Anti-diabetes therapies