DS-1150b is being developed by Daiichi Sankyo for the treatment of Type 2 Diabetes Mellitus. This is a Phase I, single-blind (subjects and principal investigator blinded, Sponsor unblinded), placebo-controlled, randomized, 2-part, sequential, single ascending dose, single center study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of single oral dose of DS-1150b in healthy subjects and subjects with Type 2 Diabetes Mellitus.