The goal of this clinical study is to learn more about the study drug, GS-4571, and how safe it is in 3 groups, i) Healthy participants, ii) Healthy non-diabetic obese participants, and iii) Non-obese participants with Type 2 Diabetes Mellitus (T2DM). The primary objectives of this study are: * To characterize the pharmacokinetics (PK) of GS-4571 following single and multiple ascending oral doses of GS-4571. * To evaluate the effect of concomitant food intake and (if conducted) a representative acid-reducing agent (proton pump inhibitor (PPI), omeprazole) on the PK of GS-4571. * To evaluate the safety and tolerability of single and multiple ascending oral doses of GS-4571.