Oral vitamin C treatment increases polymorphonuclear cell functions in type 2 diabetes mellitus patients with poor glycemic control

Abstract This study investigated the effect of vitamin C on polymorphonuclear (PMN) cell functions in type 2 diabetes (T2D) patients with poor glycemic control. We hypothesized that oral vitamin C supplementation improves PMN cell functions. Patients (14) received either a vitamin C (1000 mg/day) or placebo (anhydrous calcium hydrogen phosphate) tablet for 6 weeks and were subjected to a 6-week wash-out period, followed by a 6-week treatment cross-over period. Blood samples were collected at pre-treatment and post-treatment for PMN cell functions (by flow cytometry) and plasma vitamin C concentration. Phagocytosis was examined by incubating whole blood samples with fluoresceinisothiocyanate-labeled Staphylococcus aureus, and oxidative burst was simultaneously evaluated by adding hydroethidine. In comparison with placebo, vitamin C increased both PMN cell phagocytosis (pre-treatment: placebo, 17.8±1.6% and vitamin C, 19.0±3.4%, P=0.70; post-treatment: placebo, 16.6±1.7% and vitamin C, 27.1±2.9%, P=0.005) and oxidative burst (pre-treatment: placebo, 6.4±0.8% and vitamin C, 7.1±1.2%, P=0.60; post-treatment: placebo, 6.9±1.3% and vitamin C, 12.1±1.6%, P=0.02). The plasma vitamin C concentration elevated after vitamin C treatment as compared with that before treatment (P