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.