This study will compare the new medicine IcoSema, which is a combination of insulin icodec and semaglutide, taken once a week, to insulin glargine taken daily with insulin aspart in people with type 2 diabetes.The study will look at how well IcoSema controls blood sugar level in people with type 2 diabetes compared to insulin glargine taken with insulin aspart. Participants will either get IcoSema or insulin glargine taken with insulin aspart. Which treatment participants get is decided by chance. IcoSema is a new medicine that doctors cannot prescribe. Doctors can already prescribe insulin glargine and insulin aspart in many countries.

Participants will get IcoSema or insulin glargine together with insulin aspart. Participants must inject IcoSema once a week or inject insulin glargine once daily and insulin aspart 2-4 times a day. Participants will inject the medicines with a pen, which has a small needle, in a skin fold in the thigh, upper arm, or stomach. The study will last for about 1 year and 1 month. Participants will be asked to wear a sensor that measures participants blood sugar level all the time during an 8 week period at the beginning of the study and a 4 week period at the end of the study.

Women cannot take part if pregnant, breast-feeding or plan to get pregnant during the study period.

Inclusion Criteria:

• Male or female and age above or equal to 18 years at the time of signing informed consent.

• Diagnosed with type 2 diabetes mellitus 180 days or more before screening.

• HbA1c of 7.0-10.0 percentage (53.- 85.8 mmol/mol) (both inclusive) as assessed by central laboratory on the day of screening.

• Treated with once daily or twice-daily basal insulin (neutral protamine hagedorn insulin, insulin degludec, insulin detemir, insulin glargine 100 units/mL, or insulin glargine 300 units/mL) 20-80 units/day 90 days or more before screening. Short term bolus insulin treatment for a maximum of 14 days before screening is allowed, as is prior insulin treatment for gestational diabetes. The treatment can be with or without any of the following anti diabetic drugs with stable doses 90 days or more before screening:

  • Metformin
  • Sulfonylureas(a)
  • Meglitinides (glinides)(a)
  • DPP-4 inhibitors(a)
  • Sodium-glucose co-transporter 2 inhibitors
  • Alpha-glucosidase-inhibitors
  • Thiazolidinediones
  • Marketed oral combination products only including the products listed above.

• Body mass index (BMI) less than or equal to 40.0 kg/m^2.

  1. Sulfonylureas, meglitinides (glinides) and DPP-4 inhibitors must be discontinued at randomisation.

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.
• Anticipated initiation or change in concomitant medication (for more than 14 consecutive days) known to affect weight or glucose metabolism (e.g. treatment with orlistat, thyroid, hormones, or systemic corticosteroids).
• Treatment with any medication for the indication of diabetes or obesity other than stated in the inclusion criteria within 90 days before screening.
• Any episodes of diabetic ketoacidosis within 90 days before screening. As declared by the participant or in the medical records.
• Presence or history of pancreatitis (acute or chronic) within 180 days before screening.
• Any of the following: Myocardial infarction, stroke, hospitalization for unstable angina pectoris or transient ischaemic attack within 180 days before screening.
• Chronic heart failure classified as being in New York Heart Association Class IV at screening.
• Recurrent severe hypoglycaemic episodes within the last year (12 months) as judged by the investigator.
• Uncontrolled and potentially unstable diabetic retinopathy or maculopathy. Verified by a fundus examination performed within the past 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.