Compounds, compositions and methods for altering insulin secretion, particularly in the context of treatment of subjects having, or suspected of being at risk for having, diabetes mellitus. The compounds have the following structure (I): ##STR1##

including stereoisomers, prodrugs and pharmaceutically acceptable salts thereof, wherein W₁, W₂, X, R₁, R₂, R₃, R₄, m and n are defined herein.