Insulin
Human insulin is a peptide hormone composed of 51 amino acids and has a molecular weight of 5808 Da. The islets of Langerhans in the pancreas produces insulin. The name comes from the Latin insula for "island". Insulin's structure varies slightly between species of animals. Porcine insulin is especially close to the human version. So, people with diabetes can take in insulin got from pigs instead of producing their own insulin.