This trial is conducted in Europe. The aim of this clinical trial is to compare the pharmacodynamics (i.e. the glucose-lowering effect of the study medication over the entire observation phase from the time of administration and the efficacy period) and the pharmacokinetics (i.e. amount of the study insulin that can be determined in the blood) of a treatment with biphasic insulin aspart 30 (BiAsp 30) administered once, twice or thrice daily and biphasic human insulin 30 administered once daily in type 2 diabetic subjects

Inclusion Criteria:

• Informed consent obtained before any trial-related activities. (Trial-related activities are any procedure that would not have been performed during normal management of the subject)
• Type 2 diabetes mellitus diagnosed for at least 12 months prior to screening
• HbA1c value between 7% and 10.5% (both inclusive) at screening
• Any insulin treatment for at least 3 months prior to screening
• Body mass index (BMI): 25 - 40 kg/m2

Exclusion Criteria:

• Use of any oral antidiabetic agent within the past 6 months
• Active proliferative retinopathy or maculopathy requiring treatment within 6 months prior to screening
• Cardiac disease: NYHA class III or IV chronic heart failure (CHF), unstable angina, and/or any myocardial infarction (treated or untreated) within 6 months prior to screening
• Hepatic insufficiency (ALT or AST greater than or equal to 2 times the central laboratory's upper reference limit)
• Renal insufficiency (serum creatinine greater than or equal to 1.6 mg/dL for males; greater than or equal to
• Recurrent hypoglycaemia or hypoglycaemic unawareness
• Anaemia (haemoglobin less than 13.0 mg/dL in males and less than 12.0 mg/dL in females) (WHO criteria)
• Use of any systemic or topical medications (prescribed or non-prescribed) which may alter glucose metabolism (other than insulin products), including but not limited to: systemic or inhaled glucocorticoids, anabolic steroids, non-selective beta-blockers
• History of substance (e.g. drugs, alcohol) abuse or a positive result in the urine drug/alcohol screen or consumption of more than 14 units (women) or 21 units (men) of alcohol per week (One unit of alcohol equals about 250 mL of beer or lager, one glass of wine, or 20 mL spirits)
• Smoking of more than 20 cigarettes per day and inability to refrain from smoking during the in-house period
• Known hepatitis or positive serological tests for the hepatitis B surface antigen (HBsAg) or hepatitis C antibodies or HIV antibodies
• Uncontrolled treated/untreated hypertension (systolic blood pressure greater than or equal to 160 mmHg and/or diastolic blood pressure greater than or equal to 95 mmHg)