Potential antidiabetics. 8. 4-Arylhydrazono-N'-guanylnitrate-3-methyl-2-pyrazolin-5-ones, 4-arylazo-N'-guanylnitrate-3,5-dimethylpyrazoles, and 4-arylazo-N'-guanylnitrate-3,5-diphenylpyrazoles.