Physical crystal structures of a compound of the formula (I): are provided including the free base monohydrate thereof (form H-1) and the hydrochloric acid salt thereof, including hydrochloric acid salt containing 0.75 equivalent of H2O (form H0.75-3) and hydrochloric acid salt containing 2 equivalents of H2O (form H2-1), and hydrochloric acid salt Pattern P-5, preferably in substantially pure form, and other forms as described herein, pharmaceutical compositions containing structures of compound I or IA, processes for preparing same, intermediates used in preparing same, and methods of treating diseases such as diabetes using such structures.