Background:
Vitamin D might be beneficial in diabetic patients with
coronary artery disease (CAD) through its favorable effects on metabolic profiles and
biomarkers of
inflammation and oxidative stress.Objective: This study was performed to examine the effects of 6 mo of
vitamin D supplementation on metabolic status in diabetic patients with CAD.Methods: This randomized, double-blind, placebo-controlled clinical trial was conducted in 60
vitamin D-deficient diabetic patients with CAD aged 40-85 y. Subjects were randomly assigned into 2 groups to take either 50,000-IU
vitamin D supplements (
n = 30) or placebo (
n = 30) every 2 wk for 6 mo. Fasting blood samples were obtained at the beginning of the study and after the 6-mo intervention to quantify glycemic indicators,
lipid concentrations, and
biomarkers of
inflammation and oxidative stress.Results: Compared with placebo,
vitamin D supplementation resulted in significant reductions in fasting plasma
glucose (-14.9 ± 7.1 compared with +19.3 ± 7.1 mg/dL; P = 0.001), serum
insulin (-2.7 ± 1.1 compared with +1.8 ± 1.1 μIU/mL; P = 0.006), homeostasis model assessment of
insulin resistance (-0.7 ± 0.3 compared with +0.5 ± 0.3; P = 0.01), and β cell function (-9.1 ± 4.2 compared with +5.7 ± 4.2; P = 0.01) and a significant increase in serum
vitamin D (+6.8 ± 0.9 compared with +0.1 ± 0.9 ng/mL; P < 0.001) and the Quantitative
Insulin Sensitivity Check Index (+0.008 ± 0.004 compared with -0.007 ± 0.004; P = 0.01). In addition, changes in serum
high-sensitivity C-reactive protein (
hs-CRP; -1.0 ± 0.5 compared with +0.6 ± 0.5 μg/mL; P = 0.02), plasma
nitric oxide (NO; +7.0 ± 2.0 compared with -4.6 ± 2.0 μmol/L; P < 0.001), total
reduced glutathione (GSH; +104 ± 16.4 compared with +24.8 ± 16.4 μmol/L; P = 0.001), and
malondialdehyde concentrations (-0.2 ± 0.1 compared with +0.2 ± 0.1 μmol/L; P < 0.001) in the supplemented group were significantly different from the changes in these indicators in the placebo group.Conclusions: Overall, 6 mo of
vitamin D supplementation among
vitamin D-deficient diabetic patients with CAD had beneficial effects on
glycemic control and serum
hs-CRP, NO, GSH, and
malondialdehyde concentrations. This trial was registered on the Iranian website (www.irct.ir) for registration of clinical trials as IRCT201510315623N56.