Clinical Outcomes of Insulin Glargine U300 on Glycemic Control and Hypoglycemia: A Retrospective Observational Study

Background/Objectives: Insulin glargine U300 (IGlarU300) is a second-generation, long-acting insulin analog designed to provide a more stable pharmacokinetic profile compared to insulin glargine U100. However, long-term real-world data reflecting its long-term impact on glycemic control and hypoglycemia across diverse populations remain limited. This study evaluated the 24-month clinical outcomes of transitioning to IGlarU300 in a real-world setting. Methods: This retrospective, single-center, observational study enrolled patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM) who transitioned to IGlarU300 between 2017 and 2021. HbA1c levels, body weight, insulin doses, and hypoglycemia rates were evaluated at baseline and up to 24 months. Results: A total of 242 patients (T1DM: n = 68, T2DM: n = 174) were analyzed. HbA1c levels significantly declined at all follow-up points compared to baseline (mean change at 12 months: −0.85% 95% CI: −1.24 to −0.47%; p < 0.001]). No significant change in total insulin dose was observed over the one-year follow-up; however, improved glycemic control led to a significant reduction in oral antidiabetic medication use, reflecting successful treatment simplification and a decrease in polypharmacy burden (mean change: -0.50 95% CI: −0.70 to −0.30; p < 0.001). Notably, both severe and mild hypoglycemia episodes showed significant reductions (p = 0.010 and p = 0.019, respectively). Switching to IGlarU300 was associated with sustained improvements in glycemic control and a reduction in hypoglycemia rates. Conclusions: These findings suggest that IGlarU300 may be an effective clinical option for optimizing metabolic outcomes, though further controlled studies are warranted to confirm these observational results.