Biguanide. Biguanide can refer to a molecule, or to a class of drugs based upon this molecule. Biguanides can function as oral antihyperglycemic drugs used for diabetes mellitus or prediabetes treatment.They are also used as antimalarial drugs.The disinfectant polyaminopropyl biguanide features biguanide functional groups.iktionary (0.00 / 0 votes) Rate this definition: biguanide (Noun). The compound imidodicarbonimidic diamide derived from guanidine. biguanide (Noun). Any of a class of antihyperglycemic and antimalarial drugs based upon this compound.