The Effect of High Glucose on Oxidative Stress Response, NADH Availability, and ATP Levels. A, Schwann cells maintained at 5.6 mM normal or 25 mM high glucose for more than 8 weeks were measured for ROS formation, and after change of glucose media for 4 hours. B and D, NADH availability and ATP levels at normal and high glucose, and after change to 15 mM glucose for 48 hours. C and E, Effect of the metabolites pyruvate, lactate, and β-hydroxybutyrate ketone body (30 mM) on NADH and ATP for 48 hours. Data are represented as mean ± SEM. Means with different letters are significantly different using Bonferroni post hoc test following one-way ANOVA, P < .05.