It was January 23, 1922, when the first successful subcutaneous injection of a pancreatic extract, prepared by Banting and purified by Collip, was administered to Leonard Thompson, a young boy in diabetic ketoacidosis, at the Toronto General Hospital. That day is the birth of insulin therapy which over the years has saved tens of millions of lives of people. Animal extracted insulin has been continuously purified until human insulin and the insulin analogs have been obtained with the rDNA technique to substitute insulin according to physiology. Today basal-bolus insulin therapy in type 1 diabetes, and basal insulin in type 2 (possibly in combination with GLP-1 RA) remain the consolidated gold standards of insulin therapy in diabetes.