Adults with T1D who had participated in the “Uncovering Rare Obesity” program (through which eligible subjects were tested for genetic forms of obesity) and used incretin analogs (including GLP-1 RAs and the dual GIP/GLP-1 RA tirzepatide) for the management of obesity were enrolled in this study. Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.