When C-peptide was detectable in a subject (either at baseline or after stimulation), the hyperglycemia and GLP-1 infusion stimulated C-peptide, respectively, 2.9-fold [95% CI: 1.2–7.1, P = 0.03] and 3.5-fold [95% CI: 2.4–5.2, P < 0.001] (Fig. 2A and Supplemental Table S1). This evidence concerns the gene GCG and Hyperglycemia.