A Multiple Ascending Dose Study to Evaluate Safety and Tolerability of BFKB8488A in Participants With Type 2 Diabetes Mellitus and Participants With Non-Alcoholic Fatty Liver Disease

Inclusion Criteria: For T2DM Cohort only: * Body mass index (BMI) ≥ 27 kg/m2 and ≤ 40 kg/m2. * A confirmed diagnosis of Type 2 diabetes ≥ 6 months at screening * Current stable treatment (at least 3 months) for diabetes * Hemoglobin A1c (HbA1c) ≥ 6.8% and ≤ 9.0%. * For women of childbearing potential, agreement to remain abstinent or use reliable contraception during treatment period and for at least 42 days after last dose of study drug * For men, agreement to remain abstinent or use reliable contraception and agree to refrain from donating sperm * For NAFLD cohort only: * BMI ≥ 25 kg/m2 and ≤ 40 kg/m2 * At screening, confirmed liver fat by ultrasound OR calculated Liver Fat ≥ 10% using variables from the NAFLD liver fat score * Hepatic steatosis on magnetic resonance imaging (MRI; ≥ 10% average liver proton density fat fraction \[PDFF\]) prior to randomization. Exclusion Criteria: * Pregnant, lactating, or intending to become pregnant within 42 days after the last dose of study drug is administered * Suspected or confirmed diagnosis of Type 1 diabetes * Significant cardiac disease * Any psychiatric illness that increases the risk of participation in the study * History of severe allergic, anaphylactic, or other hypersensitivity reactions, or severe systemic bacterial, fungal, or parasitic infections * Poor peripheral venous access * Received blood products within 2 months before dosing * Donation or loss of blood within 30-56 days prior to study drug administration * Positive for hepatitis C virus (HCV) antibody, hepatitis B surface antigen (HBsAg), or human immunodeficiency virus (HIV) antibody * Liver enzymes greater than acceptable limits * History of eating disorders or surgical procedures for weight loss * Active participation in a structured weight loss or dietary program * Treatment with investigational therapy or exposure to any biological therapy * Illicit drug use, marijuana use, or alcohol abuse * Current use of more than one pack of cigarettes a day or equivalent nicotine- containing products * Any serious medical condition or abnormality in clinical laboratory tests