type 2 diabetes mellitus (diagnosed clinically) for at 12 months or longer

currently treated with basal insulin once daily or premixed insulin twice daily for at least 3 months with or without oad(s), and total daily insulin dose less than 1.4 iu (u)/kg (if treated with metformin, unchanged total daily dose of at least 1000 mg for at least 3 months)

body mass index (bmi) equal to 40 kg/m^2 or below

hba1c (glycosylated haemoglobin a1c) between 7.0% and 10.0% by central laboratory analysis

plan to be admitted for optimising glycaemic control at least 2 days prior to the randomisation

treatment with thiazolidinediones (tzd) or glucagon-like peptide-1 (glp-1) receptor agonists within the last 3 months prior to the screening

anticipated change after the randomisation in concomitant medication known to interfere with glucose metabolism, such as systemic corticosteroids, beta-blockers and mono amine oxidase (mao) inhibitors

previous participation in this trial (participation is defined as randomised. re-screening of screening failures is allowed only once within the limits of the recruitment period.)