What is significant about the primary structure of insulin?

Insulin's Primary Structure

The primary structure of insulin was one of the first protein structures to be determined, established in 1954. Insulin is a hormone that regulates blood sugar levels. Its molecule is composed of two polypeptide chains, linked to each other. One chain has 21 amino acid residues, and the other has 30. The molecular weight of insulin (M) is 5700.