A Research Study to Look at How Insulin Icodec and Semaglutide Work in the Body of People From China With Type 2 Diabetes When Given Alone or Together

Inclusion Criteria: * Chinese male or female * Aged 18-64 years (both inclusive) at the time of signing informed consent * Diagnosed with type 2 diabetes mellitus greater than or equal to 180 days prior to the day of screening * Body mass index between 18.5 and 34.9 kg/m\^2 (both inclusive) * Body weight greater than or equal to 50 kg * HbA1c (glycated haemoglobin) below or equal to 9.0% (75 mmol/mol) * Insulin naïve. However, short-term insulin treatment for a maximum of 14 days prior to the day of screening is allowed, as is prior insulin treatment for gestational diabetes * Stable daily dose(s) including any of the following anti-diabetic drug(s)/regimen within 45 days prior to the day of screening: * Any metformin formulation * DPP-4 (dipeptidyl peptidase-4) inhibitors (participants are not allowed to participate in the study if they are treated with DPP-4 inhibitors as monotherapy) * SGLT2 (sodium-glucose linked transporter 2) inhibitors * Alpha-glucosidase inhibitors * Oral combination products (for the allowed individual oral antidiabetic drugs) Exclusion Criteria: * Known or suspected hypersensitivity to trial product(s) or related products * Female who is pregnant, breast-feeding or intends to become pregnant or is of child-bearing potential and not using highly effective contraceptive method * Uncontrolled and potentially unstable diabetic retinopathy or maculopathy. Verified by a fundus examination performed within 90 days prior to 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 * Recurrent severe hypoglycaemia (more than 1 severe hypoglycaemic event within the past 180 days) or hypoglycaemic unawareness as judged by the investigator or hospitalisation for diabetic ketoacidosis within the past 180 days prior to the day of screening