In non-diabetic α-cells, glucagon secretion is regulated by several factors, notably by glucose, amino acids and free fatty acids;11,27,28 and the paracrine effectors insulin and somatostatin.9,29,30 Diabetes disrupts this fine regulation of glucagon secretion, resulting in glucagon hypersecretion and aggravation of hyperglycemia. This evidence concerns the gene GCG and diabetes mellitus.