A Research Study to See How Much CagriSema Lowers Blood Sugar and Body Weight Compared to Tirzepatide in People With Type 2 Diabetes Treated With Metformin, SGLT2 Inhibitor or Both

This study will look at how much CagriSema lowers blood sugar and body weight in people with type 2 diabetes. CagriSema is a new investigational medicine. Doctors cannot yet prescribe CagriSema. CagriSema will be compared to a medicine called tirzepatide. Doctors can prescribe tirzepatide in some countries. Participants will either receive CagriSema or tirzepatide. Which treatment the participant will receive is decided by chance. For each participant, the study will last for up to 1 year and 4 months.

Inclusion Criteria: * Male or female (sex at birth). * Age 18 years or above at the time of signing the informed consent. * Diagnosed with type 2 diabetes mellitus greater than or equal to (\>=) 180 days before screening. * Stable daily dose(s) \>= 90 days before screening of any of the following antidiabetic drug(s) or combination regimen(s) at effective or maximum tolerated dose as judged by the investigator: * Metformin * sodium-glucose co-transporter 2 inhibitor (SGLT2i) * Glycated haemoglobin (HbA1c) 7.0-10.5 percent (53-91 millimoles per mol \[mmol/mol\]) (both inclusive) as determined by central laboratory at screening. * Body mass index (BMI) \>= 30 kilogram per square meter (kg/m\^2) at screening. BMI will be calculated in the electronic case report form (eCRF) based on height and body weight at screening. Exclusion Criteria: * Female who is pregnant, breast-feeding or intends to become pregnant or is of childbearing potential and not using a highly effective contraceptive method. * Renal impairment with estimated Glomerular Filtration Rate less than \< 30 milliliter per minute per 1.73 square meter (mL/min/1.73 m\^2) as determined by central laboratory at screening. * Treatment with any anti-diabetic or anti-obesity medication (irrespective of indication) other than stated in the inclusion criteria within 90 days before screening. However, short term insulin treatment for a maximum of 14 consecutive days is allowed. * Uncontrolled and potentially unstable diabetic retinopathy or maculopathy. Verified by an eye 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.