title: Correlations between Glucagon Stimulated C-peptide Levels and Microvascular Complications in Type 2 Diabetes Patients.
abstract: BACKGROUND
  This study aimed to investigate whether stimulated C-peptide is associated with microvascular complications in type 2 diabetes mellitus (DM).
  
  
  METHODS
  A cross-sectional study was conducted in 192 type 2 diabetic patients. Plasma basal C-peptide and stimulated C-peptide were measured before and 6 minutes after intravenous injection of 1 mg glucagon. The relationship between C-peptide and microvascular complications was statistically analyzed.
  
  
  RESULTS
  In patients with retinopathy, basal C-peptide was 1.9±1.2 ng/mL, and stimulated C-peptide was 2.7±1.6 ng/mL; values were significantly lower compared with patients without retinopathy (P=0.031 and P=0.002, respectively). In patients with nephropathy, basal C-peptide was 1.6±0.9 ng/mL, and stimulated C-peptide was 2.8±1.6 ng/mL; values were significantly lower than those recorded in patients without nephropathy (P=0.020 and P=0.026, respectively). Stimulated C-peptide level was associated with increased prevalence of microvascular complications. Age-, DM duration-, and hemoglobin A1c-adjusted odds ratios for retinopathy in stimulated C-peptide value were 4.18 (95% confidence interval [CI], 1.40 to 12.51) and 3.35 (95% CI, 1.09 to 10.25), respectively. The multiple regression analysis between nephropathy and C-peptide showed that stimulated C-peptide was statistically correlated with nephropathy (P=0.03).
  
  
  CONCLUSIONS
  In patients with type 2 diabetes, the glucagon stimulation test was a relatively simple method of short duration for stimulating C-peptide response. Stimulated C-peptide values were associated with microvascular complications to a greater extent than basal C-peptides.
authors.affiliation: Division of Endocrinology and Metabolism, Konyang University Hospital, Konyang University College of Medicine, Daejeon, Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Yoon
authors.forename: Youn-Zoo
authors.initials: YZ
authors.lastname: Cho
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Byung-Joon
authors.initials: BJ
authors.lastname: Kim
authors.forename: Keun-Young
authors.initials: KY
authors.lastname: Park
authors.forename: Gwan-Pyo
authors.initials: GP
authors.lastname: Koh
authors.forename: Dae-Ho
authors.initials: DH
authors.lastname: Lee
authors.forename: Dong-Mee
authors.initials: DM
authors.lastname: Lim
keywords: Basal C-peptide; Diabetes mellitus, type 2; Glucagon stimulation test; Microvascular complications; Stimulated C-peptide