Independent Association of 25[OH]D Level on Reduced Glutathione and TNF-α in Patients with Diabetes and/or Hypertension

Abstract

Purpose: Oxidative and inflammatory pathways play a significant role in the pathophysiology of a wide variety of non-communicable diseases such as type 2 diabetes mellitus (T2DM) and hypertension. However, the effect of serum 25-hydroxyvitamin D (25[OH]D) on these pathways is still controversial. To evaluate the association of 25[OH]D on antioxidant and pro-inflammatory biomarkers, reduced glutathione (GSH) and tumor necrosis factor (TNF)-α, in T2DM and hypertensive patients. Patients and Methods: This is a cross-sectional study of a consecutive sample of patients attending the the Family Medicine clinic at King Abdullah bin Abdulaziz University Hospital (KAAUH). Participants were screened for eligibility according to the following criteria: aged above 18 years and diagnosed with T2DM and/or hypertension for at least one year. Patients receiving any kind of vitamin D or calcium supplements within the last three months were excluded, as were those with a history of renal failure, cancer, liver, thyroid, or any other chronic inflammatory diseases. Results: In total 424 T2DM and/or hypertensive patients (mean age 55±12 years) were recruited. In addition to routine physical and laboratory examinations, levels of serum 25[OH]D, GSH and TNF-α were measured. The prevalence of 25[OH]D deficiency (<50 nmol/L) was 35.1%, which was independent from GSH and TNF-α levels. In T2DM, hypertensive and patients having both diseases, GSH levels were 349.3±19, 355.4±19 and 428.8±20 μmol/L, respectively. Uncontrolled T2DM and hypertension patients showed significantly higher GSH compared with the controlled group. Males showed slightly higher level of TNF-α compared with females and uncontrolled hypertensive patients had relatively higher TNF-α level when evaluated against controlled hypertensive patients. Conclusion: 25[OH]D level is independent of oxidative stress and inflammation, assessed by levels of GSH and TNF-α, respectively, in T2DM and hypertensive Saudi patients.