Background
We aimed to investigate the significance of the C‐peptide levels on a glucagon stimulation test (GST) conducted soon after diagnosis as a predictive marker for residual β‐cell function over time in Japanese children with type 1 diabetes (TD1).
Methods
We retrospectively enrolled 65 Japanese children (25 male, 40 female; age <16 years) with new‐onset TD1. A GST was conducted within 1 month of diagnosis, when glucose toxicity improved. One‐ to 2‐h postprandial serum C‐peptide values were measured at 0, 3, 6, 12, 24, 36, 60, and 120 months after diagnosis.
Results
Receiver operating characteristic analysis showed that the cutoff values of peak serum C‐peptide levels used to predict the complete destruction of β‐cells at 3, 6, and 12 months after diagnosis were all 0.20 ng/mL (area under the curve [AUC] 0.867, 95% confidence interval [CI] 0.745–0.990; AUC 0.774, 95% CI 0.634–0.914; and AUC 0.804, 95% CI 0.695–0.914, respectively); the values at 24, 36, and 60 months were 0.69 ng/mL (AUC 0.828, 95% CI 0.721–0.936), 0.60 ng/mL (AUC 0.777, 95% CI 0.636–0.918), and 0.70 ng/mL (AUC 0.848, 95% CI 0.715–0.982), respectively. On multivariate analysis, peak serum C‐peptide level on a GST, diabetic ketoacidosis, age, and HbA1c level at diagnosis were associated with residual β‐cell function over time.
Conclusions
Peak serum C‐peptide levels on a GST conducted soon after diagnosis in Japanese children with TD1 could predict the time to decrease in postprandial serum C‐peptide values to < 0.20 ng/mL.