Diarmait Dian mac Airmetaig, also Diarmait Guthbinn, (died 689) was King of Uisnech in Mide of the Clann Cholmáin. He was the grandson of Conall Guthbinn mac Suibni (died 635), a previous king. His father Airmetach Cáech was slain at the Battle of Mag Rath in 637. Diarmait ruled from 653 to 689.
The feud between Clann Cholmáin and the SÃÂl nÃÂedo Sláine of the early 7th century had ended in victory for the SÃÂl nÃÂedo Sláine who dominated the high kingship of Ireland in the second half of the 7th century. They began to feud among themselves, and Clann Cholmain was caught up in the feud as well. In 662, a member of the cousin line of Clann Cholmáin Bicc, Fáelchú mac Máele Umai was slain at the Battle of Ogamain fighting on the side of Conaing Cuirre mac Congaile of Cnogba and Blathmac mac ÃÂedo Sláine (died 665) while fighting the adherents of Diarmait mac ÃÂedo Sláine (died 665).
Diarmait himself was killed in 689 as part of the old feud by ÃÂed mac Dlúthaig (died 701) of the Fir Cúl Breg sept of SÃÂl nÃÂedo Sláine. ÃÂed's grandfather Ailill Cruitire mac ÃÂedo Sláine was slain in battle by Diarmait's grandfather Conall Guthbinn in 634. According to the Book of Leinster, Conall Guthbinn was killed by the High King FÃÂnsnechta Fledach mac Dúnchado (died 695) of Brega.
Diarmait's sons included:
Diarmait's grandson Domnall Midi mac Murchado (died 763) was a high king of Ireland.