Application of urine C-peptide creatinine ratio in type 2 diabetic patients with different levels of renal function

Abstract

Objective: This study aims to investigate the effect of single urine C peptide/creatinine (UCPCR) in assessing the islet β Cell function of type 2 diabetes mellitus (T2DM) patients with different renal function.

Methods: A total of 85 T2DM patients were recruited in this study, all the patients were assigned to one group with estimated glomerular filtration rate (eGFR)≤60 ml·min^-1·1.73 m^-2 and another group complicated with eGFR>60 ml·min^-1·1.73 m^-2. Serum creatinine, urine creatinine, serum fasting C-peptide (FCP), fasting blood glucose (FBG), glycosylated hemoglobin (HbA1C) and 24-hour urinary C-peptide (24hUCP) were measured. The modified homeostasis model assessment-islet β cell function [HOMA-islet (CP-DM)], the modified homeostasis model assessment-insulin resistance [HOMA-IR(CP)] and UCPCR were calculated.

Results: When compared with group eGFR ≤60 ml·min^-1·1.73 m^-2, the levels of UCPCR, FCP, the modified HOMA-IR(CP) and HOMA-islet (CP-DM) were promoted and the concentrations of HbA1C, FPG, creatinine were decreased in the patients of eGFR>60 ml·min^-1·1.73 m^-2 (P<0.05); FCP was uncorrelated with 24hUCP while associated with UCPCR in the patients of eGFR ≤ 60 ml·min^-1·1.73 m^-2; UCPCR was positively correlated with FCP and HOMA-IR(CP) in the T2DM patients with different levels of renal function; the cut-off (UCPCR ≤ 1.13 nmol/g) had 88.37% sensitivity and 95.24% specificity [95% confidence interval (CI):0.919-0.997] for identifying severe insulin deficiency in T2DM patients[area under the curve (AUC) 0.978].

Conclusion: UCPCR can be used to evaluate islets β Cell function in T2DM patients with different renal function status.

Keywords: 24-hour urinary C-peptide; C peptide; EGFR; diabete; urinary C peptide/creatinine ratio.

Figure 1

When eGFR ≤ 60 mL.min-1.1.73 m-2, UCPCR was positively correlated with FCP (A) and HOMA-IR (CP) (C); When eGFR > 60 mL.min-1.1.73 m-2, UCPCR was positively correlated with FCP (B), HOMA-IR(CP) (D) and 24-h UCP (F); UCPCR was negatively correlated with duration (E).

Figure 2

The ROC curve identified a cut-off UCPCR ≤1.13 nmol/g for discriminating poor islet function in T2DM patienets (AUC 0.978) with 88.37% sensitivity and 95.24% specificity.