This study is comparing the concentration of a single dose of insulin icodec when administered in the belly, upper arm and thigh on different occasions.

Participants will receive one injection of insulin icodec on three different occasions, each time injected at a different site, i.e. either on our belly, upper arm or thigh.

The study will last for about 34 weeks. Participants will have 23 visits with the study doctor. Informed Consent (V0) visit and screening visit (V1) will be performed on two different days. The informed consent visit may be performed via telephone to minimize personal contact with site staff during the coronavirus outbreak.

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

Inclusion Criteria:

• Male or female
• Aged 18-69 years (both inclusive) at the time of signing informed consent
• Body mass index between 18.5 and 38.0 kg/m^2 (both inclusive)
• Diagnosed with type 2 diabetes mellitus above or equal to 180 days prior to the day of screening
• HbA1c (glycated haemoglobin) below or equal to 9.0 percentage at screening
• Current daily basal insulin treatment of 0.2-1.0 (I)U/kg/day (both inclusive) with or without any of the following anti-diabetic drugs/regimens with stable doses above or equal to 90 days prior to the day of screening:
• Any metformin formulation
• Other oral antidiabetic drugs: DPP-4 inhibitors / SGLT2 inhibitors / Oral combination products (for the allowed individual oral antidiabetic drugs)
• Oral or injectable GLP-1 (glucagon-like peptide 1) Receptor Agonists

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 an adequate contraceptive method (adequate contraceptive measures as required by local regulation or practice).

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