Vitamin C supplementation lowers advanced glycation end products (AGEs) and malondialdehyde (MDA) in patients with type 2 diabetes: A randomized, double‐blind, placebo‐controlled clinical trial

This study evaluated how daily vitamin C administration impacts systemic oxidative stress and inflammation and its safety in T2D patients. This randomized, double-blinded, placebo-controlled, parallel-arm clinical trial included 70 patients with T2D. They were allocated to receive either 500 mg/day of vitamin C or a matching placebo for 8 weeks. Of the 70 subjects assigned to the trial, 57 were included in the statistical analysis (vitamin C: n = 32, placebo: n = 25). Inflammatory and oxidative markers, including advanced glycation end products (AGEs), malondialdehyde (MDA), advanced oxidation protein products (AOPP), oxidized low-density lipoprotein (ox-LDL), highly sensitive C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), and ferric reducing ability of plasma (FRAP) were measured at baseline and the end of the trial. In addition, vitamin C tolerance was evaluated. A nutritionist visited all participants for a standard diabetic regimen. Following vitamin C supplementation, the serum levels of MDA (p-value < .001) and AGEs (p-value = .002) demonstrated a significant decrease after controlling for multiple confounders, including age, blood pressure, waist circumference, HbA1C, TG, and LDL-C, while no significant changes were observed for AOPP (p-value = .234) and ox-LDL (p-value = .480). The FRAP showed an increasing trend as an antioxidant marker but was not statistically significant (p-value = .312). The hs-CRP and TNF-α had no significant changes (p-value: .899 and .454, respectively). Also, no major adverse events were observed. Vitamin C supplementation may be beneficial in reducing AGEs and MDA in patients with T2D.