High Prevalence of Vitamin D Deficiency and Correlation of Serum Vitamin D with Cardiovascular Risk in Patients with Metabolic Syndrome

Background: Metabolic syndrome (MetS) identifies subjects with increased risk of cardiovascular disease when they have a combination of insulin resistance, obesity, hypertension, hyperglycemia, low high-density lipoprotein cholesterol (HDL-C), and elevated triglycerides (TGs). Increasing evidence suggests that vitamin D deficiency could be associated with diabetes and MetS. The aim is to assess if 25-hydroxyvitamin D (25-OHD) is correlated with cardiovascular risk components of MetS. Methods: A cross-sectional study involved 124 diabetic patients with MetS according to International Diabetes Federation definition. 25-OHD was measured using liquid chromatography-tandem mass spectrometry (LCMS/MS). Fasting insulin, lipid profile, glucose, and hemoglobin-A1c (HbA1c) were determined using routinely standard laboratory methods. Insulin resistance was assessed using homeostatic model assessment (HOMA). Results: 59.68% and 27.42% of patients have vitamin D deficiency and insufficiency, respectively. Systolic blood pressure (SBP) was significantly higher in patients with vitamin D deficiency compared to patients with sufficient vitamin D (P < 0.05). Serum log (25-OHD) was inversely correlated with SBP, HbA1c, low-density lipoprotein cholesterol (LDL-C), TGs, and total cholesterol and directly correlated with pancreatic b cell function (HOMA-b) (P < 0.05). Multiple linear regression analysis has shown that SBP can be predicted from log (25-OHD) (B=-9.388, P < 0.05), while HbA1c, LDL-C, TGs, total cholesterol, and HOMA-b cannot be predicted from log (25-OHD), (P > 0.05). Conclusions: Vitamin D deficiency was very prevalent among patients with MetS. 25-OHD was inversely correlated with glycemic control and cardiovascular risk components of MetS except HDL-C, insulin resistance, and obesity. SBP was the only cardiovascular risk component that can be predicted from vitamin D concentrations.