Second-generation basal insulins like glargine 300U/mL (Gla-300) have a longer duration of action and less daily fluctuation and interday variability than first-generation ones, such as glargine 100U/mL (Gla-100). The EF-BI study, a nationwide observational, retrospective study, was designed to compare persistence, acute care complications, and healthcare costs associated with the initiation of such basal insulins (BI) in a real-life setting in France. This study was conducted using the French healthcare claims database (SNDS). Adult patients living with type1 or type2 diabetes mellitus (T1DM or T2DM) initiating Gla-300 or Gla-100 ± other hypoglycemic medications between January 1, 2016 and December 31, 2020, and without any insulin therapy over the previous 6months were included. Persistence was defined as remaining on the same insulin therapy until discontinuation defined by a 6 month period without insulin reimbursement. Hospitalized acute complications were identified using ICD-10 codes. Total collective costs were established for patients treated continuously with each basal insulin over 1-3years. All comparisons were adjusted using a propensity score based on initial patient/treatment characteristics. A total of 235,894 patients with T2DM and 6672 patients with T1DM were included. Patients treated with Gla-300 were 83% (T1DM) and 44% (T2DM) less likely to discontinue their treatment than those treated with Gla-100 after 24months (p < 0.0001). The annual incidence of acute hospitalized events in patients with T2DM treated with Gla-300 was 12% lower than with Gla-100 (p < 0.0001) but similar in patients with T1DM. Comparison of overall costs showed moderate but statistically significant differences in favor of Gla-300 versus Gla-100 for all patients over the first year, and in T2DM only over a 3-year follow-up. Use of Gla-300 resulted in a better persistence, less acute hospitalized events at least in T2DM, and reduced healthcare expenditure. These real-life results confirmed the potential interest of using Gla-300 rather than Gla-100.