Carbazoles and hydrazone-bridged thiazole-pyrrole derivatives are known to exhibit a wide range of biological activities including antimicrobial activity. This work is a further extension of their biological activities that identifies a total of 13 of these derivatives as new alpha-glucosidase inhibitors. The carbazole derivatives exhibited noncompetitive inhibition of the enzyme with the inhibitor possessing the 2-benzoimidazole substitution being the most potent in the series. Compounds possessing the 2-benzothiazole, 2-benzoxazole and quinoline groups were also found to be promising for enzyme inhibition. The hydrazone-bridged thiazole-pyrrole derivatives showed competitive enzyme inhibition with a number of groups responsible for potent enzyme inhibition including 4-nitrophenyl, 4-bromophenyl, and 4-methoxyphenyl groups. Moreover, the hydrazone derivatives with unsubstituted pyrrole ring were found to be more favorable to alpha-glucosidase inhibition than the ones possessing the methyl-substituted ring. The current work may provide new structural and functional diversity to drug discovery of promising alpha-glucosidase inhibitors as anti-diabetic drugs.