title: Serum neuron-specific enolase is elevated as a novel indicator of diabetic retinopathy including macular oedema.
abstract: OBJECTIVE
  Neuron-specific enolase as a potential biomarker of diabetic retinopathy, a neurovascular disease, had not been fully explored. We aimed to investigate the relationship between NSE and diabetic retinopathy.
  
  
  METHODS
  Participants included Type 1 and Type 2 diabetes patients and healthy controls (n = 392). In this cross-sectional study, diabetic retinopathy status was assessed by fundus photographs. Serum neuron-specific enolase was measured using an electrochemiluminescence immunoassay. Co-variables for diabetic retinopathy and neuron-specific enolase were obtained from fasting blood samples and interviewer questionnaires.
  
  
  RESULTS
  Neuron-specific enolase was slightly elevated in diabetic patients, in contrast to healthy participants, and obviously increased in diabetic patients with retinopathy compared with those without [8.3 (2.0) vs. 7.6 (1.5), P = 0.037 and 8.3 (2.0) vs. 9.5 (2.7), P = 0.004, respectively]. In addition, neuron-specific enolase levels increased with and were closely correlated to the stages of retinopathy without macular oedema [r = 0.60 (0.50-0.71), P = 0.002] and stages of macular oedema with comparable retinopathy [r = 0.58 (0.46-0.69), P = 0.006]. The association of neuron-specific enolase with diabetic retinopathy was independent [odds ration (OR): 1.31 (1.12-1.65), P = 0.017], after the diabetic state and other potential confounders affecting NSE levels were considered (e.g., HbA1c , duration, age, gender, renal status and medicines). The optimal cut-off point for serum neuron-specific enolase levels for differentiating between participants with diabetic retinopathy including macular oedema and those without was 9.3 μg/l, with a sensitivity of 67.5% and a specificity of 69.8%.
  
  
  CONCLUSIONS
  Serum neuron-specific enolase is elevated in and indicative of diabetic retinopathy. Neuron-specific enolase may be a potential biomarker of diabetic retinopathy. Future prospective studies are warranted to clarify the relationship.
authors.affiliation: Endocrinology and Metabolism, Department of the First Affiliated Hospital of Nanjing Medical University, Nanjing, People's Republic of China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Yan
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Xie
authors.forename: L
authors.initials: L
authors.lastname: Yan
authors.forename: J
authors.initials: J
authors.lastname: Chen
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications; D003930:Diabetic Retinopathy / Q000097:blood* / Q000209:etiology; D005215:Fasting; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008269:Macular Edema / Q000097:blood* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D010751:Phosphopyruvate Hydratase / Q000097:blood*; D011379:Prognosis; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D010751:Phosphopyruvate Hydratase