Some substances have an antioxidant effect, and it is necessary to study their pharmacological effects and their working mechanisms. Various studies have been conducted to study the antioxidant effect of L-cysteine, and some of them state that L-cysteine has an antioxidant effect, while other scientists give conclusions that the effect of L-cysteine does not exist. . Under the influence of L-cysteine free amino acid, the amount of total protein in liver homogenate increased compared to diabetic model animals. The amount of glucose in the blood of diabetic model animals is reduced by 40% under the influence of L-cysteine. It was found that under the influence of L-cysteine, the activity of antioxidant enzymes in the liver homogenate of diabetic model animals is stimulated.