Inclusion Criteria:  Chinese male or female Aged 18-64 years (both inclusive) at the time of signing informed consent Body mass index between 18 and 38 kg/m^2 (both inclusive) HbA1c (glycated haemoglobin) below or equal to 9% at screening Current daily basal insulin treatment greater than or equal to 0.2 (I)U/kg/day greater than or equal to 60 days prior to the day of screening with or without any of the following anti-diabetic drugs/regimens with stable doses greater than or equal to 60 days prior to the day of screening: Any metformin formulation Other oral antidiabetic drugs: DPP-4 (Dipeptidyl-peptidase-4) Inhibitors , SGLT2 (Sodium-glucose co-transporter-2) 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). 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 run-in. 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