Comparative Effectiveness of Switching From First-Generation Basal Insulin to Glargine 300 U/ml or Degludec 100 U/ml in Type 1 Diabetes: The RESTORE-1 Study.

Introduction: Following pivotal trials, real-world evidence is important to assess the impact of new drugs in everyday clinical practice. The RESTORE-1 study aimed to compare effectiveness and safety of the second-generation basal insulins (2BI), i.e., insulin glargine 300 U/ml (Gla-300) vs. degludec 100 U/ml (IDeg-100), in type 1 diabetes (T1D).

Methods: Retrospective, non-inferiority, multicenter study, based on electronic medical records. All patients switching to Gla-300 or IDeg-100 from first-generation basal insulins (1BI) were 1:1 propensity score matched (PSM). Changes during 6 months in HbA1c (primary endpoint), fasting plasma glucose (FPG), body weight, and insulin doses were assessed using linear mixed models for repeated measures. Incidence rates (IR) of hypoglycemic events were assessed.

Results: Overall, 19 centers provided data on 585 patients in each PSM cohort. For both groups, statistically significant reductions in HbA1c from baseline to 6 months were documented: - 0.20%; (95% CI - 0.32; - 0.08) in the Gla-300 group and - 0.14%; (95% CI - 0.24; - 0.04) in the IDeg-100 group. The non-inferiority of Gla-300 vs. IDeg-100 was confirmed (non-inferiority margin of 0.30%; upper 95% CI at 6 months, 0.09%). No statistically significant between-group differences emerged in FPG and body weight. Dose changes of basal and short-acting insulin were small in both groups, but higher in the Gla-300 group than in the Deg-100 group (p < 0.006). Incidence rates (IR) of hypoglycemia (blood glucose ≤ 70 mg/dl and < 54 mg/dl) during the 6-month follow-up by treatment were slightly lower in the Gla-300 group than in the Deg-100 group [IR ratios 0.82 (95% CI 0.55; 1.22) and 0.83; (95% CI 0.38; 1.83), respectively]. Hypoglycemic events (blood glucose < 54 mg/dl) decreased at 6 months in both groups (p = 0.01 for Gla-300 and p < 0.001 for IDeg-100). There were no severe hypoglycemic events for Gla-300 and seven events for IDeg-100 (p = 0.02).

Conclusions: Switching from 1BI to 2BI in adults with T1D was associated with similar improvements in glycemic control and overall significant decrease in hypoglycemia, with no severe events with Gla-300. Effectiveness of both insulins was limited by under-titration.