First Research Study to Look at How Two Medicines, NNC0480-0389 and Semaglutide, Work Together in Healthy People, in People With High Body Weight and in People With Diabetes

Inclusion Criteria: Part 1: * Male aged 18-45 years (both inclusive) at the time of signing informed consent. * Body mass index between 20.0 kg/m\^2 and 29.9 kg/m\^2 (both inclusive). * Considered to be generally healthy based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator. Part 2 (not applicable for proof-of-concept (PoC) cohort): * Body mass index between 20.0 kg/m\^2 and 39.9 kg/m\^2 (both inclusive). * Female of non-childbearing potential or male aged 18-55 years (both inclusive) at the time of signing informed consent. * Considered to be eligible based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator. Part 2 (only applicable for PoC cohort): * Body mass index between 25.0 kg/m\^2 and 39.9 kg/m\^2 (both inclusive). Overweight or obesity should be due to excess adipose tissue, as judged by the investigator. * Female of non-childbearing potential or male aged 18-64 years (both inclusive) at the time of signing informed consent. * Considered to be eligible based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator. * Diagnosed with type 2 diabetes at least 90 days prior to the day of screening. * Subjects treated with diet and exercise as monotherapy or in combination with 1-2 of the following anti-diabetic drug(s) at a stable dose for at least 30 days prior to screening: metformin, sulfonylureas, meglitinides, DPP-4 inhibitors, alpha-glucosidase inhibitors, thiazolidinediones, GLP-1 receptor agonists or SLGT-2 inhibitors. The metformin dose should be between 1500 mg to 3000 mg or maximum tolerated or effective dose documented in subject's medical record. * Glycosylated haemoglobin (HbA1c) in the range of 6.5% (inclusive) and 10% (non-inclusive). Exclusion Criteria: Part 1: * Any disorder which in the investigator's opinion might jeopardise subject's safety or compliance with the protocol. * HbA1c equal to or above 6.5 % (48 mmol/mol) at screening. * Use of prescription medicinal products or non-prescription drugs, except routine vitamins, occasional use of acetaminophen, ibuprofen and acetylsalicylic acid, or topical medication not reaching systemic circulation within 14 days prior to the day of screening. Presence or history of any clinically relevant respiratory, metabolic, renal, hepatic, cardiovascular, gastrointestinal, or endocrinological conditions. Part 2 (not applicable for PoC cohort): * Any disorder (except for conditions associated with T2D for the PoC cohort) which in the investigator's opinion might jeopardise subject's safety or compliance with the protocol. * Presence or history of any clinically relevant respiratory, metabolic, renal, hepatic, cardiovascular, gastrointestinal, or endocrinological conditions (except conditions associated with T2D for PoC Cohort). * Use of prescription medicinal products or non-prescription drugs, except routine vitamins, occasional use of acetaminophen, ibuprofen and acetylsalicylic acid, or topical medication not reaching systemic circulation within 14 days prior to the day of screening. * HbA1c equal to or above 6.5 % (48 mmol/mol) at screening. Part 2 (only applicable for PoC cohort): * Any disorder (except for conditions associated with T2D for the PoC cohort) which in the investigator's opinion might jeopardise subject's safety or compliance with the protocol. * Presence or history of any clinically relevant respiratory, metabolic, renal, hepatic, gastrointestinal, or endocrinological conditions (except conditions associated with T2D for PoC Cohort). * Use of any prohibited medications as listed in the protocol within 14 days of screening. * Use of prescribed medications at the time of screening at a dose that had not been stable within 30 days prior to screening.