NGF and diabetic neuropathy: In this review, biomarkers for diabetic neuropathy are divided into four groups: (a) AGE-related molecules (methyl glyoxal and glyoxalase I), (b) molecules that participate in the progression of inflammation (Toll-like receptors, TNF-α, miR-146a, adiponectin, etc.), (c) molecules associated with nerve damage (nerve specificity enolase and semaphorin), and (d) molecules involved in nerve protection (nerve growth factor and HSP27).