Objective To compare the efficacy and safety of two insulin intensification strategies in patients inadequately controlled on once-daily basal insulin glargine + metformin and/or pioglitazone. Methods This multinational, randomised, open-label, parallel-arm, phase IV trial compared efficacy and safety of LM25 and Basal Plus (BP) (+ metformin and/or pioglitazone) over 24 weeks in patients with T2D and HbA1c 7.5- 10.5% despite basal-only insulin regimen (BO) and fasting plasma glucose ≤ 6.7 mmol/L. The primary objective was to assess non-inferiority (NI) of LM25 vs BP (margin 0.4%). Results Patients (mean [SD] age 57.5 [9.52] years) were randomised to LM25 (n = 236) or BP (n = 242). Estimated change (least squares [LS] mean [95% CI]) in HbA1c at 24 weeks was -1.30 (-1.44, -1.16)% with LM25 and -1.08 (-1.22, -0.94)% with BP. LM25 was shown to be NI to BP (LS mean [95% CI]) treatment difference -0.22 (-0.39, -0.05); gated superiority assessment showed a statistically significant advantage for LM25 (p=0.010). LS mean (95% CI) daily self-monitored blood glucose (SMBG) levels fell to 8.03 (7.82, 8.23) mmol/L with LM25 and to 8.14 (7.93, 8.35) mmol/L with BP at 24 weeks. Patients in both groups had similar hypoglycaemia rates and safety profile. Conclusion In patients with T2D inadequately controlled on once-daily basal insulin glargine + metformin and/or pioglitazone, intensification with LM25 or BP improved glycaemic control. HbA1c reduction was greater with LM25 than with BP. Both regimens were similarly tolerated. LM25 is therefore a valid strategy to intensify insulin treatment in patients inadequately controlled with a BO.