Glucagon stimulation test as a possible predictor of residual β-cell function

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).

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.

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.

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.