Aim: We compared the efficacy and safety of insulin degludec/insulin aspart co-formulation (IDegAsp) twice-daily to a free combination of basal insulin degludec and GLP-1 receptor agonist liraglutide (IDeg+Lira) once-daily for patients with inadequately controlled type 2 diabetes on insulin therapy and oral antidiabetic drugs. Subjects and Methods: Eligible patients were randomly allocated at a 1:1 ratio to receive either the once-daily dual-injection of IDeg+Lira (n=24) or twice-daily single-injection of IDegAsp (n=28). The primary endpoints were: HbA1c changes over 52 weeks of treatment and the percentage of participants achieving HbA1c<7.0% at week 52. Results: After 52 weeks, HbA1c decreased by 0.3% in the IDegAsp group and by 0.7% in the IDeg+Lira group. The HbA1c reduction was greater in the IDeg+Lira group than in the IDegAsp group. 19% of patients on IDegAsp versus 40% on IDeg+Lira achieved HbA1c<7.0%. Pre-breakfast and pre-dinner blood glucose at 52 weeks were significantly lower in the IDeg+Lira group than in the IDegAsp group. The reduction in body mass index (BMI) was greater in the IDeg+Lira group than in the IDegAsp group throughout the study period. The confirmed hypoglycemia rates were 1.32 and 0.69 per patient/year of exposure to IDegAsp and IDeg+Lira, respectively. Conclusions: In patients with inadequately controlled type 2 diabetes on insulin therapy and oral antidiabetic drugs, treatment with the once-daily dual-injection of IDeg+Lira compared to the twice-daily single-injection of IDegAsp showed no significant difference in glycemic control, but with a slightly larger reduction in HbA1c at 52 weeks, and statistically superior weight loss.