ENO2 and Renal insufficiency: The study concluded that NSE levels not only increased with but also were intimately correlated to the stages of neuropathy.13 Serum cystatin C (CysC) levels were also reported significantly higher in DPN patients and those elevated serum CysC levels were associated with DPN independent of covariables.24 Despite these positive results, none of the above-mentioned biomarkers are related directly to the structure of nerve itself, which might overlap with disorders affecting other systems, such as a generalized inflammatory state, renal insufficiency, and lung tumor.