• Female of non-childbearing potential, or male.

• For United States (US) only: Female of childbearing potential using highly effective non-systemic methods of contraception with low user-dependency and willingness to continue using it through-out the study or male.

• Age 18-75 years (both inclusive) at the time of signing the informed consent.

• Diagnosed with type 2 diabetes mellitus greater than or equal 180 days before screening.

• Stable daily dose(s) more than or equal 90 days before screening of the following antidiabetic drug(s) or combination regimen(s) at effective or maximum tolerated dose as judged by the investigator: metformin with or without sodium-glucose co-transporter 2 (SGLT2) inhibitor.

• Glycated haemoglobin (HbA1c) of 7.5-10.0% (58-86 millimoles per moles (mmol/mol)) (both inclusive) as assessed by central laboratory at screening.

• Body mass index (BMI) greater than or equal 23.0 kilograms per meter square (kg/m\^2).