This trial is conducted in Europe. The aim of the trial is to investigate the safety, tolerability, pharmacokinetics (the exposure of the trial drug in the body) and pharmacodynamics (the effect of the investigated drug on the body) of NNC0123-0000-0338 (insulin 338) in subjects with type 2 diabetes.

Inclusion Criteria:

• Male subject, or female subject of no childbearing potential, if surgically sterilized (i.e. tubal ligation, bilateral oopherectomies (removal of both ovaries and both fallopian tubes) or hysterectomised) for at least 3 months or if postmenopausal (i.e. as defined by amenorrhoea for at least 12 months prior to screening and documented by follicle stimulating hormone (FSH) levels above 40 U/L)
• Body mass index (BMI) between 20.0 and 35.0 kg/m^2 (both inclusive)
• Type 2 diabetes mellitus (as diagnosed clinically) for 12 months or more

Exclusion Criteria:

• Known or suspected hypersensitivity to trial products or related products
• Presence of clinically significant acute gastrointestinal symptoms (e.g. nausea, vomiting, heartburn or diarrhoea) within 2 weeks prior to dosing, as judged by the Investigator
• Any chronic disorder or severe disease which in the opinion of the Investigator might jeopardise subject's safety or compliance with the protocol