Cyclocondensation of α-halogenacetophenones with an original 4-morpholine thiosemicarbazide was used to synthesize a group of new Captions: of the 1,3,4-thiadiazine group, containing a thiomorpholine fragment at position 2 of the thiadiazine ring. Two members of this group of compounds were found to produce effective inhibition of nonenzymatic protein glycosylation in an in vitro model system. These test results allow compounds containing phenyl and fluorophenyl fragments IIIa and IIIb to be recommended for further study in in vivo experiments.