Relationship between serum C-peptide level and diabetic retinopathy according to estimated glomerular filtration rate in patients with type 2 diabetes

Abstract

ObjectiveTo 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). DesignA 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−11.73m−2): patients without renal impairment (eGFR ≥60) and those with renal impairment (eGFR <60). ResultsIn 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. ConclusionsSerum C-peptide levels are inversely associated with the prevalence of DR in type 2 diabetic patients independently of eGFR.