Efficacy and Safety of Basal-bolus Therapy, Comparing Stepwise Addition of Insulin Aspart Versus Complete Basal-bolus Regimen

Inclusion Criteria: * Type 2 diabetes (diagnosed clinically) for at least 12 months * Basal insulin treatment (NPH once or twice daily, insulin glargine once daily or insulin detemir once daily) for at least 6 months * HbA1c: 7.0-9.0 % (both inclusive) by central laboratory analysis (one retest analysed at the central laboratory within a week is permitted with the result of the last sample being conclusive) * BMI (Body Mass Index) less than 40.0 kg/m\^2 Exclusion Criteria: * Previous use of pre-mix or bolus insulin (allowed is previous use of bolus insulin only in case of a hospitalisation or a severe condition requiring intermittent use of bolus insulin for less than 14 consecutive days, but not during the last 6 months prior to screening visit (Visit 1) * Use of GLP-1 (Glucagon-like peptide-1) receptor agonists or pramlintide within the last 6 months prior to prior to screening visit (Visit 1) * Anticipated change in concomitant medication known to interfere significantly with glucose metabolism (e.g. systemic corticosteroids, beta-blockers, MAO (Monoamine oxidase) inhibitors, etc.) * Cardiovascular disease, within the last 12 months prior to screening visit (Visit 1), defined as: stroke; decompensated heart failure New York Heart Association (NYHA) class III or IV; myocardial infarction; unstable angina pectoris; or coronary arterial bypass graft or angioplasty * Uncontrolled treated/untreated severe hypertension (systolic blood pressure sitting at least 180 millimetre (mm) mercury (Hg) and/or diastolic blood pressure at least 100 mmHg). For Argentina: systolic blood pressure sitting at least 150 mmHg and/or diastolic blood pressure at least 90 mmHg * Impaired liver function, defined as ALAT (Alanine aminotransferase) at least 2.5 times upper limit of normal (one retest analysed at the central laboratory within a week is permitted with the result of the last sample being conclusive) * Impaired renal function defined as serum creatinine above 135 micromol/L (above 1.5 mg/dL) for males and above 110 micromol/L (above 1.2 mg/dL) for females; and, if required by the locally applicable metformin label, glomerular filtration rate below 60 ml/min, calculated by the Cockroft \& Gault formula). One retest within a week is permitted with the result of the last sample being conclusive * Recurrent severe hypoglycaemia (more than 1 severe hypoglycaemic episode, during the last 12 months) or hypoglycaemic unawareness as judged by the Investigator or hospitalisation for diabetic ketoacidosis during the previous 6 months * Proliferative retinopathy or maculopathy requiring treatment according to the Investigator * Treatment with OADs (Oral anti-diabetic drug) contraindicated or unapproved for combination treatment with insulin (according to local OAD label)