CagriSema for Type 2 Diabetes

Inclusion criteria: * Male or female (sex assigned at birth, inclusive of all gender identities). * Age 18 years or above at the time of signing the informed consent. * Diagnosed with type 2 diabetes mellitus (T2DM) greater than or equal to (≥) 180 days before screening. * Stable once-weekly dose ≥ 90 days before screening of branded s.c. semaglutide. Branded semaglutide s.c. includes Ozempic and Wegovy. Participants on compounded semaglutide are ineligible. * Not on treatment with oral antidiabetic drugs or on stable daily dose(s) ≥ 90 days before screening of any of the following antidiabetic drug(s) or combination regimen at effective or maximum tolerated dose (MTD) as judged by the investigator: metformin and/or sodiumglucose co-transporter-2 (SGLT2) inhibitor. * Glycated haemoglobin (HbA1c) 6.5-10.5 percentage (%) (48-91 millimoles per mole \[mmol/mol\]) (both inclusive) as determined by central laboratory at screening. * Body mass index (BMI) ≥ 25 kilograms 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 from screening. * Renal impairment with estimated glomerular filtration rate (eGFR) 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 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 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. * A self-reported change in body weight \> 5% within 90 days before screening irrespective of medical records. * Use of personal continuous glucose monitoring (CGM) devices. Participants currently using personal CGM devices must discontinue use prior to screening and throughout study participation.