This is an exploratory trial with two cross-over arms investigating pharmacokinetic profiles of endogenous and exogenous insulin in type 2 diabetes mellitus patients treated with continuous subcutaneous Insulin Aspart infusion and combined with or without intravenous glucose infusion. The order of treatment session will be randomised.

Hypotheses:

1. Secretion of endogenous insulin depends on exogenous insulin supply
2. Secretion of endogenous insulin is depends on plasma glucose levels

There are a screening visit and two treatment sessions:

Session A: Treatment with Insulin Aspart 1.5 IE/time overnight without intravenous glucose infusion Session B: Treatment with Insulin Aspart 1.5 IE/time overnight with intravenous glucose infusion.

Inclusion Criteria:

• Subjects with type 2 diabetes mellitus
• Insulin-naive patients
• HbA1C < 9%
• Women and men >= 35 and <= 75 years old
• BMI 25-42 kg/m2, both values are included

Exclusion Criteria:

• Suspected or known allergy to the trial drug or similar medications
• Treatment with hte drugs that after Investigator judgment could potentially interfere with plasma glucose levels
• Heart: Unstable angina pectoris, acute myocardial infarction within the last 12 months
• Severe uncontrolled hypertension with blood pressure in lying position > 180/110 mmHg
• Impaired liver function with liver parameters more than 2 times above the upper normal limit according to the local laboratory
• Impaired kidney function with eGFR < 50 ml/min according to the local laboratory
• Pregnancy, lactation or desire for pregnancy in the study period and for women in childbearing age without adequate contraception-adequate contraception is: sterilisation, hysterectomy or current use of contraceptive pills, coil, gestagen depot injection, subdermal implantation, hormonal vaginal ring and transdermal depot patch.