An American Company, Eli Lily, produced Human Insulin in 1983.
Human Insulin is formed as Proinsulin in the Pancreas by the beta cells of Islets of Langerhans. The pro insulin gas 3 chains – Chain A, B and C. The pro insulin gets matured into Insulin by joining Chains A and B by disulphide bonds. Eli Lily, prepared two DNA sequences corresponding to A and B chains of Human insulin. They introduced them in plasmids of E.coli to produce insulin chains . Chain A and Chain B were produced separately. These chains were then linked by creating disulphide bonds to form Human Insulin.