561-P: Serum C-Peptide Concentrations Are Inversely Associated with Cardiovascular Autonomic Neuropathy in Type 2 Diabetic Individuals With and Without Renal Impairment Independently of Estimated Glomerular Filtration Rate

Cardiovascular autonomic neuropathy (CAN) is a significant cause of cardiovascular morbidity and mortality in patients with type 2 DM. C-peptide is suggested as a bioactive peptide with protective roles on microangiopathy. However, due to renal metabolism of C-peptide, previous studies have been limited to diabetic patients without renal impairment. Serum C-peptide levels might be increased despite reduced beta cell function in patients with renal impairment. Therefore, we tested the hypothesis that C peptide would relate to the risk of CAN in patients with type 2 DM independently of renal function. A total of 1070 type 2 diabetic patients were investigated in this cross-sectional study. Prior dialysis or renal transplantation was excluded. CAN was diagnosed by a cardiovascular reflex test. Fasting C-peptide, 2-hour postprandial C-peptide, and ΔC-peptide levels were measured. The estimated glomerular filtration rate (eGFR) was calculated from CKD-EPI equation. In individuals with and without renal impairment, patients with CAN showed lower levels of fasting C-peptide, postprandial C-peptide and ΔC-peptide. In multivariate analysis, serum C-peptide levels were significantly associated with CAN (OR, 0.80; 95% CI, 0.67-0.96 for fasting C-peptide, p=0.014; OR, 0.78; 95% CI, 0.64-0.95 for postprandial C-peptide, p=0.013; OR, 0.80; 95% CI, 0.66-0.97 for ΔC-peptide, p=0.023) after adjustment for age, gender and other confounders including eGFR. Our results show that serum C-peptide levels are inversely associated with CAN in type 2 diabetic patients with and without renal impairment independently of eGFR. These findings might suggest the beneficial effects of serum C-peptide levels on CAN independently of eGFR.