TNF and Hyperglycemia: The mechanism by which hyperglycemia causes painful diabetic neuropathy is still unknown, but elevated blood glucose is at the origin of an increase in advanced glycation end products, protein kinase C isoform activation, mitochondrial dysfunction, and activation of nuclear factor-κB (NF-κB) [4, 5] with important release of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) [6].