title: Postprandial C-peptide to glucose ratio as a predictor of β-cell function and its usefulness for staged management of type 2 diabetes.
abstract: OBJECTIVE
  Type 2 diabetes is characterized by progressive deterioration of β-cell function. Recently, it was suggested that the C-peptide-to-glucose ratio after oral glucose ingestion is a better predictor of β-cell mass than that during fasting. We investigated whether postprandial C-peptide-to-glucose ratio (PCGR) reflects β-cell function, and its clinical application for management of type 2 diabetes.
  
  
  METHODS
  We carried out a two-step retrospective study of 919 Korean participants with type 2 diabetes. In the first step, we evaluated the correlation of PCGR level with various markers for β-cell function in newly diagnosed and drug-naïve patients after a mixed meal test. In the second step, participants with well-controlled diabetes (glycated hemoglobin <7%) were divided into four groups according to treatment modality (group I: insulin, group II: sulfonylurea and/or dipeptityl peptidase IV inhibitor, group III: metformin and/or thiazolidinedione and group IV: diet and exercise group).
  
  
  RESULTS
  In the first step, PCGR was significantly correlated with various insulin secretory indices. Furthermore, PCGR showed better correlation with glycemic indices than homeostatic model assessment of β-cell function (HOMA-β). In the second step, the PCGR value significantly increased according to the following order: group I, II, III, and IV after adjusting for age, sex, body mass index and duration of diabetes. The cut-off values of PCGR for separating each group were 1.457, 2.870 and 3.790, respectively (P < 0.001).
  
  
  CONCLUSIONS
  We suggest that PCGR might be a useful marker for β-cell function and an ancillary parameter in the choice of antidiabetic medication in type 2 diabetes.
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea ; International Health Care Center Yonsei Medical Health System Seoul Korea.
authors.forename: Sena
authors.initials: S
authors.lastname: Hwang
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Seo Hee
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Yong-Ho
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: A Ra
authors.initials: AR
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Youngki
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Byung-Wan
authors.initials: BW
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Eun Seok
authors.initials: ES
authors.lastname: Kang
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Ahn
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Bong Soo
authors.initials: BS
authors.lastname: Cha
authors.affiliation: Department of Internal Medicine Yonsei University College of Medicine Seoul Korea.
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Lee
keywords: C‐peptide; Pancreatic β‐cell; Type 2 diabetes mellitus