A cost-effectiveness analysis was conducted to compare insulin glargine 300 U/mL (Gla-300) versus insulin degludec 100 U/mL (IDeg-100) in insulin-naïve adults with type 2 diabetes (T2D) sub-optimally controlled with oral anti-diabetic drugs (OADs). The BRAVO diabetes model was used to assess costs and outcomes for once-daily Gla-300 versus once-daily IDeg-100 from a US healthcare sector perspective. Baseline clinical data were based on BRIGHT, a 24-week, non-inferiority, randomised control trial comparing Gla-300 and IDeg-100 in adults with T2D sub-optimally controlled with OADs (with or without glucagon-like peptide-1 receptor agonists). Treatment costs were based on doses observed in BRIGHT as well as net prices. Costs associated with complications were based on published literature. Lifetime costs (US$) and quality-adjusted life-years (QALYs) were predicted and used to calculate incremental cost-effectiveness ratio estimates; extensive scenario and sensitivity analyses were conducted. Overall lifetime medical costs were estimated to be $327,904 and $330,154 for people receiving Gla-300 and IDeg-100, respectively; insulin costs were $43,477 and $44,367, respectively. People receiving Gla-300 gained 8.024 QALYs and 18.55 life-years, while people receiving IDeg-100 gained 7.997 QALYs and 18.52 life-years. Because Gla-300 was associated with a cost-saving of $2250 and 0.027 additional QALYs, it was considered to be dominant compared with IDeg-100. Results of the scenario and sensitivity analyses confirmed the robustness of the base case results. Gla-300 was the dominant treatment option compared with IDeg-100 based on the willingness-to-pay threshold of $50,000/QALY. Results remained robust against a wide range of alternative assumptions on key parameters.