GCG and obesity due to melanocortin 4 receptor deficiency: This is important not only because GLP-1 receptor agonists have become very popular as pharmaceutical drugs to treat diabetes and obesity (JY Wang et al.), but also because, as we will see later, GLP-1 prevents amyloidosis of the amyloidogenic small peptide hormone amylin, which is normally released along with insulin from the pancreatic β-cells when blood sugar levels are elevated.