Introduction: Insulin glargine 300 U/mL (Gla-300; Toujeo ®) is a second-generation oncedaily basal insulin. Previous randomized controlled trials showed comparable HbA1c reductions with lower rates of hypoglycemia of Gla-300 versus Gla-100. Patients and Methods: We report the 12 months results of the Swiss cohort of Toujeo-1, a prospective, observational multicenter study exploring the real-world effectiveness of Gla-300 in adult patients with type 2 diabetes (T2D) uncontrolled (HbA1c 7.5-10%) on oral therapy and compared these to the overall Toujeo-1 cohort (conducted in Switzerland and Germany). Primary endpoint was the percentage of patients achieving individual HbA1c targets. Secondary endpoints included changes in HbA1c, fasting plasma glucose (FPG), body weight, insulin dose, incidence of hypoglycemia and overall safety. Results: The analysis included 47 patients (14 women) with a mean age of 64.1 years and a diabetes duration of 8.4 years. Swiss physicians determined a higher HbA1c treatment target (7.4 vs. 7.0%) and patients received higher Gla-300 doses at baseline (20.2 vs. 14.7 units/day) and the 12-month follow-up (31.0 vs. 26.2 units/kg) than in the total cohort (n=721). After 12 months, the addition of Gla-300 reduced HbA1c by 1.5% (p<0.0001) to an HbA1c of 7.2%, and FPG by 3.3 mmol/L (p<0.0001) to an FPG of 7.1 mmol/L. At 12 months, 70.2% achieved their individual HbA1c target, more than in the overall Toujeo-1 cohort (49.9%). Body weight remained stable throughout. Only episodes of symptomatic, non-severe hypoglycemic events were documented (2.1%) with similar rates as for the overall Toujeo-1 population. Conclusion: In patients with T2D on oral therapy and newly treated with basal insulin, Gla-300 improves glycemic control with a low risk of hypoglycemia and no increase of body weight. The results for Switzerland are consistent with those reported for the overall Toujeo-1 cohort and reveal that treatment targets and approaches slightly differ between both countries.