Sample Handling
For the analysis of C-peptide and insulin, blood samples were collected in serum collection tubes. For the analysis of glucagon, glucose-dependent insulinotropic polypeptide (GIP) and GLP-1, blood samples were collected in EDTA tubes containing aprotinin and a dipeptidyl-peptidase IV inhibitor. All collection tubes were centrifuged at 3000 rpm at 4 °C for 10 minutes and stored at −80 °C until analysis. PPG were measured by a Dexcom G6 continuous glucose monitoring system (Dexcom, Inc., USA).