Diabetes mellitus (DM) is a considerably diagnosed metabolic disease and a serious problem worldwide. We prepared various zinc complexes and studied their potential for use as new antidiabetic agents. In this study, we synthesized a seleniferous zinc complex, di(2-selenopyridine-N-oxidato)zinc(II) ([ZPS]) that has a Zn(Se 2 O 2 ) coordination mode. Analyses of structure-activity relationships between its insulin-like activity and the coordination mode of [ZPS]-related complexes showed that it had high insulin-like activity. Hypoglycemic effects of [ZPS] on type 2 diabetic KK-A y mice were exerted at the lowest dose administered (1.25–2.5mg Zn/kg body weight), unlike previously synthesized zinc complexes. Furthermore, [ZPS] afforded us a new advantage; we were able to investigate the tissue distribution of the ligand by measuring the amount of selenium in the organs of [ZPS]-treated mice. Gastrointestinal absorption and tissue penetration of zinc derived from [ZPS] in ddY mice, which was monitored using an isotope tracer technique, was significantly increased compared to that of ZnCl 2 . These results suggest that [ZPS] has superior antidiabetic effects compared to previously reported zinc complexes, and is thus a potential novel antidiabetic agent that facilitates the possibility of organoselenium ligands as new metal delivery systems for treating DM.