Study of GS-4571 in Healthy Participants, Nondiabetic Obese Participants, and Nonobese Participants With Type 2 Diabetes Mellitus (T2DM)

Key Inclusion Criteria: * Age 18 through 55 years, for Parts A, B, and C, and 18 through 65 years, for Part D. * Individuals must be glucagon-like peptide-1 receptor agonist (GLP-1RA) naïve OR last dose was at least 6 months prior to screening. * Part A (SAD) and Part B (Food/PPI Effect): eligible individuals in Cohorts 1-4, (optional cohort 5) and 6 will include healthy individuals with BMI of ≥ 19 and \< 30 kg/m\^2, and no significant medical history. Individuals will also be in good general health as determined by the investigator at the screening evaluation performed no more than 28 days prior to the scheduled first dose. * Part C (MAD in nondiabetic obese individuals): Eligible individuals in Cohorts 7-9 and (optional cohort 10) will be individuals with obesity with BMI ≥ 30 kg/m\^2 and \< 45 kg/m\^2 with a total body weight \> 50 kg, and nondiabetic (HbA1c \< 6.5%). Eligible individuals will also be individuals with stable body weight (\< 5% change) for 90 days prior to screening visit based on individual report. * Part D (multiple doses in non-obese T2DM): eligible individuals in Cohort 11 will be individuals with T2DM HbA1c ≥ 7.0% and ≤ 10.5% with BMI of ≥ 19 and \< 30 kg/m\^2 and treated with diet and/or exercise, and/or metformin monotherapy. Key Exclusion Criteria: * Have any serious or active medical or psychiatric illness (including depression) that, in the opinion of the investigator, would interfere with individual treatment, assessment, or compliance with the protocol. This would include acute pancreatitis, or history of pancreatitis, acute gallbladder disease, and renal, cardiac, hematological, hepatic, pulmonary (including chronic asthma), endocrine (including diabetes \[with the exception of T2DM for individuals included in Part D only\]), central nervous, gastrointestinal (including an ulcer), vascular, metabolic (thyroid disorders, adrenal disease), immunodeficiency disorders, active infection, or malignancy that are clinically significant or requiring treatment. * Current symptoms of diabetic retinopathy or examination indicating diabetic retinopathy within one year of screening. * Any electrolyte disturbances identified at screening considered to be clinically significant in the opinion of the investigator (eg, hypokalemia, hypocalcemia, or hypomagnesemia). * Any condition that could lead to electrolyte disturbances (eg, eating disorder) in the opinion of the investigator. * History of syncope, palpitations, or unexplained dizziness. * Active, or history of, significant cardiac disease or conduction abnormality * History of implanted defibrillator or pacemaker. * Have been treated with the following within 6 months prior to screening or is expected to receive these agents during the study: GLP-1RAs, systemic steroids, immunosuppressant therapies, or chemotherapeutic agents (eg, corticosteroids, immunoglobulins, other immune or cytokine-based therapies). * Previously stopped use of GLP-1RAs secondary to severe side effects including nausea, constipation, diarrhea, or emesis. Note: Other protocol defined Inclusion/Exclusion criteria may apply.