The effect of peptide Lys-Glu-Trp-NH₂ in doses of 0.2, 20, and 2000 μg/kg on lipid and carbohydrate metabolism was studied in Wistar rats with experimental hyperlipidemia and diabetes mellitus. This tripeptide in a dose of 2000 μg/kg produced a hypolipidemic effect on atherogenic lipoproteins, decreased the intensity of LPO, improved the state of the antioxidant system, and normalized the content of HDL. Treatment with this tripeptide had a hypolipidemic effect and reduced the severity of specifi c morphofunctional changes in the pancreatic and hepatic tissue.