GLP1R and obesity due to melanocortin 4 receptor deficiency: However, disease states (e.g., obesity, Cushing’s syndrome, type 1 diabetes [T1D] and anorexia nervosa) and some commonly used drugs [e.g., glucocorticoids and glucagon-like peptide 1 receptor agonists (GLP-1RAs)] that impact pancreatic β-cell insulin secretion can also alter the GH/IGF-I axis.