This study will look at how well a new medicine called NNC0519-0130 helps people with type 2 diabetes lower their blood sugar and body weight. The study will test up to 7 different doses of NNC0519-0130. Which treatment participant will get is decided by chance. Participants will take 1-3 injections once a week. The study medicine will be injected under skin with a thin needle in the stomach, thigh, or upper arm. The study will last for about 40 weeks.

Inclusion Criteria:

• 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).

Exclusion Criteria:

• Treatment with any medication for the indication of diabetes or obesity other than stated in the inclusion criteria within 90 days before screening. However, short term insulin treatment for a maximum of 14 consecutive days and prior insulin treatment for gestational diabetes are allowed.
• Uncontrolled and potentially unstable diabetic retinopathy or maculopathy. Verified by a fundus examination performed within 90 days before screening or in the period between screening and randomisation. Pharmacological pupil-dilation is a requirement unless using a digital fundus photography camera specified for non-dilated examination.
• Known hypoglycaemic unawareness as indicated by the investigator according to Clarke's questionnaire question.

According to the Novo Nordisk disclosure commitment on novonordisk-trials.com

Sponsor staff involved in the clinical trial is masked according to company standard procedures. The study will be double-blinded within dose level of once weekly subcutaneously administered NNC0519-0130 and the corresponding volume-matched placebo arms. The active comparator arm with tirzepatide will be open label.