title: Serum bilirubin concentrations are positively associated with serum C-peptide levels in patients with Type 2 diabetes.
abstract: OBJECTIVE
  To investigate the relationship between physiological serum total bilirubin concentrations and serum C-peptide levels in Korean patients with Type 2 diabetes.
  
  
  METHODS
  A total of 588 patients with Type 2 diabetes were investigated in this cross-sectional study. Fasting C-peptide level, 2-h postprandial C-peptide level and ΔC-peptide (postprandial C-peptide minus fasting C-peptide) level were measured in all patients.
  
  
  RESULTS
  Fasting C-peptide level, postprandial C-peptide level and ΔC-peptide level tended to be higher in patients with higher bilirubin concentrations. Partial correlation analysis showed that serum bilirubin levels were significantly correlated with fasting C-peptide level (r = 0.159, P < 0.001), postprandial C-peptide level (r = 0.209, P < 0.001) and ΔC-peptide level (r = 0.186, P < 0.001) after adjustment for other covariates. In the multivariate model, the association between serum bilirubin concentrations and serum C-peptide levels remained significant after adjustment for confounding factors including age, gender, familial diabetes, hypertension, hyperlipidaemia, BMI, HbA1c , duration of diabetes and associated liver function tests (fasting C-peptide level: β = 0.083, P = 0.041; postprandial C-peptide level: β = 0.106, P = 0.005; ΔC-peptide level: β = 0.096, P = 0.015, respectively).
  
  
  CONCLUSIONS
  Serum bilirubin concentrations within the physiological range were positively associated with serum C-peptide levels in patients with Type 2 diabetes.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Republic of Korea.
authors.forename: J O
authors.initials: JO
authors.lastname: Chung
authors.forename: D H
authors.initials: DH
authors.lastname: Cho
authors.forename: D J
authors.initials: DJ
authors.lastname: Chung
authors.forename: M Y
authors.initials: MY
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D001663:Bilirubin / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002096:C-Peptide / Q000097:blood*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D018450:Disease Progression; D005215:Fasting; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital; D018384:Oxidative Stress / Q000187:drug effects; D019518:Postprandial Period; D056910:Republic of Korea
chemical_list: D015415:Biomarkers; D002096:C-Peptide; D007004:Hypoglycemic Agents; D007328:Insulin; D001663:Bilirubin