title: Relationship between serum C-peptide level and diabetic retinopathy according to estimated glomerular filtration rate in patients with type 2 diabetes.
abstract: OBJECTIVE
  To test the hypothesis that serum C-peptide level would relate to the risk of diabetic retinopathy (DR) in type 2 diabetic patients independently of estimated glomerular filtration rate (eGFR).
  
  
  METHODS
  A total of 2,062 patients with type 2 diabetes were investigated in this cross-sectional study. Fasting C-peptide, 2-hour postprandial C-peptide, and ΔC-peptide (postprandial C-peptide minus fasting C-peptide) levels were measured. The patients were divided into two groups according to eGFR (ml∙min(-1)1.73m(-2)): patients without renal impairment (eGFR ≥60) and those with renal impairment (eGFR <60).
  
  
  RESULTS
  In subjects both with and without renal impairment, patients with DR showed lower levels of fasting C-peptide, postprandial C-peptide and ΔC-peptide. In multivariate analysis, serum C-peptide levels were significantly associated with DR (odds ratio [OR] of each standard deviation increase in the logarithmic value, 0.85; 95% confidence interval [CI], 0.78-0.92 for fasting C-peptide, P<0.001; OR, 0.87; 95% CI, 0.82-0.92 for postprandial C-peptide, P<0.001; OR, 0.88; 95% CI, 0.82-0.94 for ΔC-peptide, P<0.001) after adjustment for age, gender, and other confounding factors including eGFR.
  
  
  CONCLUSIONS
  Serum C-peptide levels are inversely associated with the prevalence of DR in type 2 diabetic patients independently of eGFR.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, 8 Hak-Dong, Dong-Gu, Gwangju, 501-757, Republic of Korea.
authors.forename: Jin Ook
authors.initials: JO
authors.lastname: Chung
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, 8 Hak-Dong, Dong-Gu, Gwangju, 501-757, Republic of Korea.
authors.forename: Dong Hyeok
authors.initials: DH
authors.lastname: Cho
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, 8 Hak-Dong, Dong-Gu, Gwangju, 501-757, Republic of Korea.
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Chung
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, 8 Hak-Dong, Dong-Gu, Gwangju, 501-757, Republic of Korea. Electronic address: mychung@chonnam.ac.kr.
authors.forename: Min Young
authors.initials: MY
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D002096:C-Peptide / Q000097:blood*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000097:blood* / Q000453:epidemiology / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology
chemical_list: D002096:C-Peptide
keywords: C-peptide; Diabetic retinopathy; Glomerular filtration rate; Peptide hormones; Type 2 diabetes mellitus