GPR15 and diabetes mellitus: In order to gain mechanistic insights into the beneficial effects of butyrate induced Tregs in the GALT in diabetes remission, we first analyzed the expression of gut homing receptors, CCR9 (CD199), GPR15 and α4β7 in the Tregs in the GALT as well as the PLN, pancreas, and spleen in hyperglycemic NOD mice.