Abstract: Organic peptide containing substances with insulin-like activity derived from blood or a blood component of a warm-blooded animal, which comprises the steps of pre-treating the blood or blood component by adjusting the pH thereof to a value of from 2 to 4 or of from 8 to 10, incubating the pre-treated blood at a temperature of from about 15 to about 40.degree. C for a period of at least four hours, cooling the incubated blood to a temperature of less than 10.degree. C, and recovering from the treated blood after neutralization organic peptide substances having a molecular weight of from about 1000 to about 5000, and an insulin-like activity of from about 14 to about 40 .mu.U/mg solid.