In in vitro experiments demonstrated the ability of 1,3,4-thiadiazines differing substituents in the position 2- and 5- of heterocyclic ring, exhibit antioxidant activity and ability to block protein glycation. In in vitro screening results, selected a group of 1,3,4-thiadiazines, showed the ability to correct metabolic disorders (hyperglycemia, accumulation of protein glycation products and free-radical oxidation of lipids) in alloxan diabetes in rats. The mechanisms of action in vivo and interrelation "structure - activity" of the compounds discussed. This work was supported RSF grant, project number 16-15-00039.