Abstract: hGH(1-43) having the formula: H--Phe--Pro--Thr--Ile--Pro--Leu--Ser--Arg--Leu--Phe--Asp--Asn--Ala--Met--L eu--Arg--Ala--His--Arg--Leu--His--Gln--Leu--Ala--Phe--Asp--Thr--Try--Gln--G lu--Phe--Glu--Glu--Ala--Try--Ile--Pro--Lys--Glu--Gln--Lys--Tyr--Ser--OH has been found to have remarkable insulin-potentiating action, as has the fragment hGH (17-43). Pharmaceutical compositions in accordance with the invention include hGH(1-43), hGH(17-43) or a biologically active intermediate fragment, or a nontoxic salt thereof, dispersed in a pharmaceutically acceptable carrier. Such peptides or pharmaceutically acceptable salts thereof may be administered to mammals to promote the action of insulin.Such a peptide can be synthesized by exclusively solid-phase techniques, by partial solid-phase techniques, by fragment condensation, by classical solution addition or by recently developed recombinant DNA techniques.