Eli Lilly, an American company, prepared two DNA sequences corresponding to the A and B chains of human insulin and introduced them in the

Eli Lilly, an American company, prepared two DNA sequences corresponding to the A and B chains of human insulin and introduced them in the plasmid of Escherichia coli . By introducing the DNA sequences encoding insulin chains into the plasmids of Escherichia coli, the bacteria can be used as mini-factories to produce insulin. This method of using genetically engineered bacteria to produce human insulin revolutionized the treatment of diabetes and allowed for large-scale production of insulin for therapeutic use.